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2020 | Book

CIGOS 2019, Innovation for Sustainable Infrastructure

Proceedings of the 5th International Conference on Geotechnics, Civil Engineering Works and Structures

Editors: Dr. Cuong Ha-Minh, Dr. Dong Van Dao, Prof. Dr. Farid Benboudjema, Prof. Dr. Sybil Derrible, Dr. Dat Vu Khoa Huynh, Dr. Anh Minh Tang

Publisher: Springer Singapore

Book Series: Lecture Notes in Civil Engineering


About this book

This book presents selected articles from the 5th International Conference on Geotechnics, Civil Engineering Works and Structures, held in Ha Noi, focusing on the theme “Innovation for Sustainable Infrastructure”, aiming to not only raise awareness of the vital importance of sustainability in infrastructure development but to also highlight the essential roles of innovation and technology in planning and building sustainable infrastructure. It provides an international platform for researchers, practitioners, policymakers and entrepreneurs to present their recent advances and to exchange knowledge and experience on various topics related to the theme of “Innovation for Sustainable Infrastructure”.

Table of Contents

Correction to: Machine learning based tool for identifying errors in CAD to GIS converted data

In the original version of the book, the following belated corrections are to be incorporated.

Mohamed Badhrudeen, Nalin Naranjo, Ali Movahedi, Sybil Derrible

Keynote Lectures

Four Decades of Computing in Civil Engineering

This paper presents the author’s perspective on four decades of computing in civil engineering. Examples of research by the author and his associates published during the past four decades are briefly described. They include artificial intelligence and expert system technology, computer-aided design and engineering (CAD/CAE), computer animation, object-oriented technology, database management, solid modelling, parallel processing and supercomputing, distributed computing on a cluster of workstations, neural networks, evolutionary computing and genetic algorithms, case-based reasoning, machine learning, fractality and chaos theory, wavelet transform, and web-based computing. It is argued that the introduction of novel computing ideas into the oldest engineering field has made the field more exciting. It has helped create new technologies such as semi-active vibration control and health monitoring of large structures and intelligent freeways, and automate processes that were unthinkable otherwise.

Hojjat Adeli
Industrialized Construction of Medium Span Concrete Bridges Using Movable False Work

Modern geometrical requirements for high capacity ground infrastructure, as highways or high-speed train lines, imply increasing numbers of long tunnels and viaducts in mountainous countries. Moreover, for the sake of the environment, only some selected construction methods are eligible for sensitive areas. Long viaducts are usually solved by means of medium span concrete viaducts. For the sake of quality and health and safety, industrialized construction methods, as launching girders or precast construction, is usually preferred. The paper will describe the pros and cons of some construction methods using movable trusses to hold in place either the formwork or precast segments, emphasizing the possibilities of reducing the critical path. New construction sequences, non-standardized structural details, static and dynamic tests, reinforcing criteria, structural response, finite element model analysis and recent already built examples will be described to illustrate the possibilities of the methods.

Jose Turmo
Using Simulation to Estimate and Forecast Transportation Metrics: Lessons Learned

In recent years transportation planners and engineers have begun to utilize traffic simulation models to estimate and forecast new transportation operations and reliability metrics. For example, the Highway Capacity Manual, Sixth Edition: A Guide for Multimodal Mobility Analysis (HCM-6) has recently adopted 1) passenger car estimation methods that are based on the microsimulation model VISSIM, and 2) urban arterial reliability estimation methods that are based on a Monte Carlos simulation technique. The advantage to simulation methods is that the metrics, which may be based on central tendency (e.g. mean, median), dispersion (variance, percentile), or even a combination of other metrics (e.g. reliability index), may be easily calculated and/or estimated. For this reason, the number of metrics developed and used has continued to increase. As one example, many researchers over the past decade have focused on developing and estimating metrics related to network reliability and resilience. However, it is an open research question on when and where these simulation approaches are appropriate to use. This paper will discuss a number of issues related to using simulation for estimating transportation metrics with a focus on model assumptions and model calibration. Specific examples from realworld test beds will be provided. Lastly, the paper will provide an overview of lessons learned and areas of future research.

L. R. Rilett
eHighway – An Infrastructure for Sustainable Road Freight Transport

In all countries, road transport with heavy vehicles will have a high share in future freight transport. When using fossil fuels for those vehicles, the resulting emissions of carbon dioxide and pollutants such as particulate matter and nitrogen dioxide put a risk on the environment and on human health. Since heavy vehicles are already contributing significantly to greenhouse gas emissions, the “eHighway” system was developed, and it was identified as a possible solution to counteract these problems. The eHighway system allows trucks to be fed with electric energy from a catenary which is mounted above the road. An efficient implementation of such system requires studies in different fields to understand the impacts of the eHighway system on today’s road infrastructure. For that purpose, the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety is funding three field trials, and the ELISA project is the most advanced of them. In ELISA, a 5 kilometer section of the motorway A5 in the German Federal State of Hessen is equipped with the eHighway system in both directions. The project is led by the respective road authority Hessen Mobil, and Technische Universität Darmstadt is responsible for the accompanying research. This contribution explains the contribution of road freight transport to greenhouse gas emissions and discusses approaches to make this transport sector more sustainable. The basics of the eHighway technology are briefly presented. The layout of the ELISA test track on motorway A5, the arrangements for the test operation, and the research program for the field test are described.

Manfred Boltze
Innovation Reduces Risk for Sustainable Infrastructure

Society and standards require more and more “risk-informed” decisions. The paper demonstrates the potential of reducing risk by implementing reliability and risk concepts as a complement to conventional analyses. Reliability evaluations can range from qualitative estimates, simple statistical evaluations to full quantitative probabilistic modelling of the hazards and consequences. The paper first introduced recent innovative developments that help reduce risk. Risk assessment and risk management are briefly touched upon. An example of the application of the new stress testing method is given. The usefulness of the seminal (1969) Observational Method is discussed. The need for developing sustainable and holistic civil engineering solutions is also briefly mentioned. The paper concludes that reliability-based approaches provide useful complementary information, and enable the analysis of complex uncertainties in a systematic and more complete manner than deterministic analyses alone. There is today a cultural shift in the approach for design and risk reduction in our profession. Reliability and risk-based approaches will assist preparing sustainable engineering recommendations and making risk-informed decisions.

Suzanne Lacasse
Applying a National BIM Model to Vietnam’s National Implementation of BIM: Lessons Learned from the UK-Vietnam Collaboration for the Industry

This paper applies the national BIM strategy method as described by the EU BIM Task Group and the UK’s Centre for Digital Built Britain to Vietnam’s development of a national digitalization vision. It will describe UK experience in promoting digital construction through BIM application in construction and facility management activities toward Smart city based on 4 strategic areas: Foundation of Public leadership; Communicate vision and foster communities; Build a common, collaborative framework; and Grow Industry Capacity. International collaboration on the national introduction of BIM is growing between countries and between governments. In 2018, the UK and Vietnam signed an MOU for collaborating on the introduction of BIM to the national plan of Vietnam started under the Prime Minister’s decision no. 2500/QĐ-TTg dated December 22nd, 2016. This paper applies the national BIM method to identify (1) the experience of the UK’s national BIM strategy, (2) Vietnam’s lessons learned of its national implementation of BIM and (3) proposals and recommendations for Vietnam’s Construction Industry.

Adam Matthews, Binh Ta

Advanced Modeling and Characterization of Structures

Advanced Analysis Software for Steel Frames

The manuscript shows an advanced analysis software of steel frames under static loadings. Input and output processes are programed using C++ and FORTRAN. A visual graphic interface for the advanced analysis software is coded for modeling easily and showing the result performance of analyzing structures. The proposed software uses stability functions (SF) to predict the second-order effects on the structures. The plastic hinge approach (PHA) and the fiber plasticity approach (FPA) are integrated in the advanced analysis software. The Generalized Displacement Control Algorithm (GDCA) is utilized for capturing the behavior of frames. A steel 3D frame is analyzed aim to validate the accuracy and time efficiency of developed software.

Phu-Cuong Nguyen, My Ngoc-Tra Lam, Duc-Duy Pham, Trong-Nghia Nguyen, Phong Thanh Nguyen
Finite Element Modelling for Axially Loaded Concrete-Filled Steel Circular Tubes

This study presents a Finite Element Analysis modelling (FEA) for Concrete-Filled Steel Circular Tubes (CFSCT) subjected to axial compressive load using the commercial FEA software ABAQUS. A new stress-strain relationship for concrete is established using the experimental data collecting from literature review. Concrete-Damaged Plasticity Model (CDPM) is employed in this study. A new softening regime is proposed for the behavior of confined concrete, and this study also introduces new parameters for constitutive model of concrete when we input into the ABAQUS software. The proposed analysis result is more accurate than the one of previous studies in the case of high-strength concrete or thin-walled steel tubes.

Duc-Duy Pham, Phu-Cuong Nguyen
Fracture Analysis of Crack Propagation on the Diaphragm of Steel Bridge Structures

The crack failure occurring on the steel diaphragm of Vam Cong Bridge during construction stage in Viet Nam has raised issues that it is necessary to deeply understand the behavior of steel structures in the construction process along with the boundary conditions of structures and especially pre-defects within steel materials. Fracture theory should be applied to analyze the brittle failures in this case which it is totally different from conventional failure at plasticity state. The investigation analyzes the fracture mechanism of a typical steel diaphragm structure that is similar to the diaphragm member of main span in the Vam Cong Bridge. Initial cracks within steel material being used for the diaphragm will be considered. The result would contribute to clarify the reasons of the brittle failure in steel bridge beams as well as crack patterns with different boundary conditions.

Tran The Truyen, Nguyen Duc Hieu, Bui Thanh Tung, Doan Bao Quoc, Nguyen Thuong Anh
A Study on Combination of Two Friction Dampers to Control Stayed-Cable Vibration Under Considering its Bending Stiffness

The stayed-cable is one of vital component of cable-stayed bridges. Stayed-cable is often very long with a small diameter and low mass, which can be considered horizontal flexible structure with very low natural frequency. Under the influence of cyclic load in specific conditions, stayed-cable can store the energy and vibrate with large amplitude. This paper focuses on studying the methods of two-friction damper combination for reducing the cable vibration, and evaluates the capacity of friction-damper parameters in mitigating the vibration of stayed-cable. The results show the relationship between the damping factor of stayed-cable and various parameters such as Equivalent viscous constants, friction, spring constant, points attached damper to stayed-cable. For long-span cable-stayed bridges, cable has relatively large diameter and it is normally covered by grouting mortar or Epoxy. Consequently, its bending stiff-ness is considerably increased. Therefore, it is necessary to take into account its bending stiffness during the vibration analysis process. From these results, designers can assess and choose the attaching point as well as parameters of friction damper, which are optimal for specific stayed-cable.

Duy-Thao Nguyen, Duy-Hung Vo
Design Proposal and Behavior Simulation of Prestressed Concrete Slab Track at Highway-Railway Grade Crossings

This paper presents the design proposal of the prestressed concrete slab (PSCS) track used for highway-railroad grade crossings in Vietnam. A new type of highway-railroad grade crossings is being proposed to replace the traditional panel crossings made by reinforced concrete, asphalt concrete and rubber. Numerical simulation was carried out to analyze the structural behavior of the PSCS. The results show that the structural proposal of the PSCS meets the requirements of stability and strength under the standard loads of truck and train engines recommended in Vietnamese specifications.

Pham Van Hung, Tran The Truyen, Tran Anh Dung, Doan Bao Quoc, Le Hai Ha, Nguyen Hong Phong
Effects of Random Road Roughness on Dynamic Impact Factor of Multi-span Super T Girder Bridge with Link Slab due to Moving Vehicles

The purpose of paper analyzes influence of random road roughness on dynamic impact factor of Bridge subjected to a moving vehicle. The road roughness is assumed by a stationary random process. The bridge has three spans which is modeled by FEM. The moving vehicle has three axles and is idealized by 6-DOFs. Monte-Carlo method is used to create the random road roughness input. The governing equation of dynamic vehicle-bridge interaction is established by means of d’Alembert’s principle. Galerkin method and Green theory are applied to discrete the governing equation in the space domain. In this paper, Runge-Kutta methodology was used to solve the governing equation in the time domain. After analyzing with a series profile of road roughness input, it is going to obtain the response of bridge output which is also the random process. The FEM analysis totally agrees with the test results of KhueDong Bridge. Furthermore, the road roughness also was investigated to clarify the effects on dynamic impact factor.Finally, when road roughness condition changes from the type A to type E, dynamic impact factor has risen considerably.

Xuan-Toan Nguyen, Duy-Thao Nguyen
Advanced Design Software for Steel Cable-Stayed Bridges Using Nonlinear Inelastic Analysis

Cable-stayed bridges have gained much popularity owing to their esthetic appearance, efficient utilization of structural materials, and technical advantages. When the main span length becomes longer, more accurate analysis methods are required to predict the realistic behaviors of structures, especially in design of steel cable-stayed bridges where nonlinear behaviors such as structural material and geometric nonlinearities are considerable. This paper presents an innovative software, named as PAAP3D, for nonlinear inelastic analysis of steel cable-stayed bridges subjected to static and seismic loadings. The solver of the PAAP3D is developed using the FORTRAN programming language, while the pre- and post-processors of PAAP3D are written using C++ programming language with a user-friendly and easy-to-use interface. The pylons, girders, and cross-beams are modeled as plastic-hinge beam-column elements where P – Δ and P − δ effects, the initial geometric imperfection, and the gradual stiffness degradation are considered. The stay cables are modeled as catenary elements to capture the cable sag effect. The generalized displacement control method (GDC) is used to solve the static analysis, and a time-history dynamic analysis is employed for seismic analysis. Some examples of steel cable-stayed bridges subjected to both static and seismic loads are studied.

Viet-Hung Truong, Seung-Eock Kim
Blind Source Separation Technique for Operational Modal Analysis in Presence of Harmonic Excitation

Operational modal analysis (OMA) known as response-only modal identification, is extremely useful for large structures in civil engineering where the excitation is difficult or even impossible to measure. The unknown excitation is always assumed as white noise in OMA. In presence of harmonics, the white noise assumption is not verified that makes the modal identification process difficult, and eventually leading to biased results. In recent years, blind source separation (BSS) techniques have been shown to be robust and efficient for OMA. In this paper, a new BBS technique termed Sparse Component Analysis (SCA) without white noise assumption, is applied for operational modal identification in presence of harmonics. The performance of the proposed method is demonstrated using numerical examples of a two-degrees-of-freedom system and a cantilever beam.

Van-Dong Do, Thien-Phu Le, Alexis Beakou
Investigation Into The Response Variability of A Higher-Order Beam Resting on A Foundation Using A Stochastic Finite Element Method

This study deals with the response variability of a beam resting on an elastic foundation using a stochastic finite element method (SFEM). Use of SFEM for a higher-order beam on an elastic foundation with a random field of elastic modulus is proposed. This random field of elastic modulus is assumed to be a one-dimensional Gaussian random field. A random field is discretized by a weighted integration method to build the stochastic finite element formulation. A numerical example is presented to validate the proposed formulation, and the results are compared with those obtained using Monte Carlo simulation. The response variability of the beam and effect of the parameter of the random field are investigated in detail.

Ta Duy Hien, Bui Tien Thanh, Nguyen Ngoc Long, Nguyen Van Thuan, Do Thi Hang
Fatigue Analysis of Jack-up Leg Structures in Transit condition

In transit condition, jack-up platform is a type of floating structures with large dimension. In towing duration, legs of the self-elevating unit are elevated, so they do not directly subject to wave and current loads but only resist inertia loads due to motion induced wave and other loads. Actually, fatigue damages of the jack-up legs structure in transit condition have not been studied clearly yet. However, Registers and Consultancy have been used 20% of total fatigue life for transit life time in the analyses and designs [1]. The percentage is approximately value, which has not accurately reflected the fatigue life in transit condition. To have the more accurately results, it is necessary to solve two important problems which are motions analysis and determination of inertia forces on the legs structure induced by the motions. These problems will be made clearly in the article and applied for 400 ft jack-up platform fabricated in Viet Nam.

Dinh Quang Cuong, Vu Dan Chinh
Finite element modeling of the TECCO protection system for rock-fall under impact loading

The TECCO protection system consists of the high strength components such as the high tensile steel (HTS) wire mesh and the high strength thread bar. This system is used in the construction for slope stabilization, ground support, landslide protection, especially rock-fall protection. The purpose of this study was to predict the behavior of the wire mesh under impact loading of rock-fall. A finite element has been constructed in order to model the impact between a rock of 0.5 tons and a rectangular wire mesh with high velocity. The mechanical response of the HTS material is assumed as elastic-plastic-isotropic material. Further, the contact behavior within the steel wire mesh and rock-fall are also considered in the model using the Coulomb friction model. Thanks to ABAQUS/Explicit based on finite element method, the impact phenomenon will be clarified. The model may help to reduce the number of experiments with high cost.

Tran Van Dang, Tran Dong, Dennis Gross
The study on the behavior of the simply supported beam steel bridge structure without the intermediate bracing system in the construction stage

Steel bridge structure without intermediate bracing systems (IBS) has been proposed. This structure has only been applied to the continuous I beam bridges in Japan. The construction of continuous bridges has many difficulties because of the solution of the deck cracking at the negative moment positions. That solution is complicated and time-consuming. Moreover, the overall instability of main girder during construction stage is not considered. For simplifying the construction process as well as avoid-ing above mentioned problem, the steel bridge structure without IBS has been innovated for the simple span structure. Then, the models of the proposed structure and the traditional steel bridge structure are simulated in construction stages in which the over-all instability usually occurs. In addition, the destruction of structure caused by construction load exceeding the bearing capacity of this structure also frequently happens. Therefore, from analyzed data of those simulation the result could be found that 1) the influence of the bar density (number of bars over an area unit) on the stability of the proposed structure is only really clear when it reaches a specific value; 2) meanwhile, the thickness of steel plate strongly affects to overall stability of this structure; and 3) despite this structure’s collapse due to the overall instability its material is still not used to its full ability.

Van Nam Le, Anh Rin Nguyen, Lien Thuc Pham, Ngoc Thi Huynh
Seismic behaviour of rammed earth walls: a time history analysis

Rammed earth (RE) is a soil-based construction material which attracts scientific researches because of its sustainable properties. This paper presents a numerical study to investigate the in-plane seismic behaviour of RE walls. First, an in-situ RE wall was modelled by the discrete element method (DEM). The robustness of the model was checked by comparing dynamic properties of the model with the experimental values. Then, an earthquake excitation was introduced to the model to assess the seismic behaviour of the RE wall studied. The signal was scaled at different amplitudes to assess the damages following different earthquake intensities. The drifts were recorded and the seismic behavior was discussed.

Quoc-Bao Bui, Tan-Trung Bui
Analysis of Two-Directional Seismic Deterioration of Steel Box Columns

This paper addresses the deterioration of the steel box column subjected to simultaneous biaxial moment and axial force, which caused local buckling, consequent decrease in base shear capacity and eventual collapse of a full-scale 4-story steel building tested at the E-Defense shake table. Two-directional deterioration was observed in the columns which were subjected to a major few cycles in a particular direction and later to the largest cycle in a significantly rotated direction. The multi-spring (MS) element that consists of springs discretizing the column cross section was used to analyze the moment deterioration by local buckling.

Tran Tuan Nam
Numerical analysis of double-layered asphalt pavement behaviour taking into account interface bonding conditions

Bonding conditions between pavement layers have an important influence on the responses of pavement structure. This paper deals with numerical analysis for the stresses, strains and deflections of double-layered asphalt pavement structure. The constitutive relations are based on the layered homogeneous half-space theory developed by Burmister (1943). In this work, in order to improve the modelling, the actual interaction between the layers is taken into account by considering a horizontal shear reaction modulus which represents the interface bonding condition. The numerical model is validated and applied through an original case study where falling weight deflectometer (FWD) tests are carried out on two full-scale pavement sections with two different bonding conditions at the interface between asphalt layers. The results indicate that the considered numerical model allows evaluating and quantifying the interface bonding condition in determining by backcalculation the horizontal shear reaction modulus at the pavement interface.

Minh Tu Le, Quang-Huy Nguyen, Mai Lan Nguyen
Parametric numerical study on a novel energy harvester using iron-gallium alloy and strain response

With the aim of contributing to efficient structural health monitoring approaches, this study proposes a micro energy-harvesting strain gauge, utilizing iron-gallium alloy, capable of generating electrical energy from dynamic strain responses. The iron-gallium alloy is a ductile magnetostrictive material with a high piezomagnetic constant, good machinability, and a large inverse magnetostrictive effect by which magnetization can be varied by mechanical stress. The device has a simple structure: a combination of a flat plate of iron-gallium alloy and a stainless steel frame, the former attached to the latter. A variation in stress applied at the alloy plate yields a time variation of the flux generating a voltage on the wound coils. The strain data is also measured at the same time. To achieve high efficiency in both power generation and deformation measurement, effective design for the novel device is required. Therefore, prototype finite element models were constructed based on the number of commercial designs available on the market. Then, parametric studies were carried out by changing the shapes, heights, and widths of the devices in order to examine their possible effects on the deformation behavior of the proposed structure. Finally, design procedures for the proposed device were recommended based on these numerical studies.

Tuan Minh Ha, Saiji Fukada, Toshiyuki Ueno
Numerical investigation of derailment loading on composite fibre transoms for implementation in the Sydney Harbour Bridge

This paper investigates the behaviour of composite fibre transoms subjected to derailment loading through a numerical analysis. The timber transoms currently installed on the Sydney Harbour Bridge railway track are soon to be replaced due to their low service lifespans and regular maintenance requirements. Whilst steel and concrete alternatives achieve elongated service lives, each possess unique limitations associated with installation and serviceability. In light of this, recent studies have focused on the development of composite fibre technology (CFT) transoms. Whilst previous studies have analysed CFT transom response to static and quasi-static loading conditions, limited research is available regarding the performance of composite fibre transoms, when subjected to derailment induced impact loading. In order to bridge this knowledge gap, numerical analysis have been utilised to investigate the internal stress distribution and detailed failure behaviour of Wagner’s CFT transoms, under impact loading.

Olivia Mirza, Maryam Hosseini, Micah Fountain
Finite Element Analysis of Reinforced Concrete beams subjected to combined actions

An enhanced multi-fiber beam element suitable for the analysis of reinforced concrete members subjected to combined loadings is presented. The model is developed using displacement-based formulation with small displacement assumption. The section kinematics is based on the kinematic assumptions of a two-node Timoshenko beam and enhanced by introducing additional degrees of freedom at each section in order to take into account the warping phenomenon. A system of fixed points is created and interpolated by Lagrange functions and polynomials. In order to take into account the contribution of stirrups, a discretization of control sections into different regions following its material response is applied. As a result, the basic assumptions of the Modified Compression Field Theory with a secant-stiffness formulation is used to represent the constitutive material model for reinforced concrete. The model is validated by comparing to the theoretical formulations and several experimental tests. The simulations include a variety of monotonic load conditions under bending, shear and torsion for specimens with rectangular section.

Tuan-Anh Nguyen, Quang-Huy Nguyen, Hugues Somja
Resistance of Cross Laminated Timber Members Under Axial Loading—A Review of Current Design Rules

Cross laminated timber (CLT) has become an important type of engineered timber product due to its superior material properties, making it suitable for mass timber construction. CLT is manufactured from naturally grown sources, and hence, it offers significant environmental benefit within the construction sector in comparison to its traditional counterparts such as concrete and steel. As a naturally grown material, timber products possess some inherent variabilities in material properties. These uncertainties make it difficult to develop universally accepted design rules for timber products, as the basic material properties may vary significantly based on its origin. This paper presents a review of current design rules for CLT under axial loads. Design procedures outlined in Eurocode, North American and Chinese standards as well as other relevant CLT handbooks have been thoroughly investigated. Experimental evidences available from literature have been used to compare the performance of those design guidance in predicting axial resistance of CLT members, where appropriate. Overall, it was observed that despite having considerable variations in mechanical properties, similar reliability concepts are adopted for specifying characteristic values, design values as well as for devising design rules for CLT structures. Once the design rules are critically evaluated based on test evidences, some design rules for CLT members under ultimate limit states have been summarised herein.

Xin Li, Mahmud Ashraf, Mahbube Subhani, Bidur Kafle, Paul Kremer
A Current-State-of-the-Art on Design Rules Vs Test Resistance of Cross Laminated Timber Members Subjected to Transverse Loading

Cross laminated timber (CLT) is an innovative and environmentally sustainable engineered timber product which has superior in-plane and out-of-plane bending strength compared to other conventional timber products. CLT panels can be used as both wall and floor elements in low-rise to mid-rise construction. Nevertheless, both shear and bending strength (along with other material properties as well) of CLT panels can vary significantly depending on the species used to manufacture these products. As a result, in-depth research with respect to the variations in bending and shear properties of CLT panels from different parts of the world is required in order to generate a common standard. However, no standardised design procedures for CLT can be found in the open literature, at this stage. The main purpose of this paper is to investigate various available design rules outlined in Eurocode, North American standards, Chinese standards and handbooks for CLT in regards to in-plane and out-of-plane bending and shear design of panels subjected to transverse loading. In addition to the theoretical review, available testing standards to obtain relevant characteristic properties have been included. Lastly, the ultimate limit states design method based on different theoretical models available for CLT elements subjected to transverse loading (such as, gamma method, k-method, shear analogy method, representative volume sub-element (RVSE) method and in-plane beam method) are also discussed and summarized at the end.

Xin Li, Mahbube Subhani, Mahmud Ashraf, Bidur Kafle, Paul Kremer
A Further Study on Stay Cable Galloping Under Dry Weather Condition

Wind-induced cable vibrations can be classified into several types such as buffeting due to wind gust, vortex-induced vibration, classical galloping with iced cables, wake galloping, parametric excitation, Reynolds number related drag instability, rain–wind induced vibration, high-speed vortex excitation and dry galloping. Among these vibration types, vortex induced vibration and buffeting due to wind gust are generally small amplitude while the last three types are mainly related to stay cables with larger amplitude vibration and the rain–wind induced vibration is the one most frequently observed on site of bridge. Furthermore, mechanism of rain–wind vibration has been fully elucidated in recent years, and some effective control methods have been successfully applied in practice. In particular, dry galloping is still less understood and it would require research that is more intensive. Hence, the aim of this paper is to elucidate the cable vibration characteristic in no rain condition (called “Dry galloping”) by wind tunnel test. Finally, the detail of its generation mechanism will be investigated and discussed.

Vo Duy Hung, Nguyen Duy Thao
Stress-Dependent Permeability of the Fractured Rock Masses: Numerical Simulation Based on the Embedded Fracture Continuum Approach

In this work, the Embedded Fracture Continuum (EFC) approach will be used to model the stress-dependent permeability of the fractured rock masses. This novel approach allows incorporating explicitly the fracture networks in the porous rock mass by using the fracture cell concept which represents the grid mesh intersected by at least one fracture. More precisely, in the EFC approach, each fracture cell represents an equivalent porous medium that the concept of continuum model can be straightforwardly applied. The numerical simulations will take into account the closure/opening effect due to the non-linear behavior of fractures with respect to normal stress as well as the shear-dilation effect. A damage law of the intact rock that undergoes yield tensile strength is also considered to model the new flow connections between fractures. Through some numerical applications, we highlighted the influence of different parameters on the effective permeability of fractured rock masses.

Hong-Lam Dang, Duc-Phi Do, Dashnor Hoxha
Improved Rigid-Plastic Method for Predicting the Ultimate Strength of Concrete Walls Restrained on Three Sides

The modern-day popularity of tilt-up construction, shear walls and concrete cores in multi-storey buildings means that the construction of concrete walls with various boundary conditions and higher slenderness ratios, along with the presence of openings, has become common. The design of such elements under eccentric axial loads, however, could be outside the restrictions of current major design codes such as the Eurocode 2 (EC2-2004), the American Concrete Institute Code (ACI318-2014) and the Australian Concrete Standard (AS3600-2018). There have been many experimental and numerical studies on the behaviour of both one-way action walls and two-way action walls supported on four sides, with and without openings in the range of high slenderness ratios (up to 50). Efforts have also been made to develop design models capable of predicting the axial load capacity of such walls. However, research into the behaviour of two-way action walls supported on three sides (TW3S walls) is still relatively unexplored and further studies in this area are needed. Recent research has demonstrated that a rigid-plastic approach could be used to describe the behaviour of TW3S walls with and without openings. Although predictions obtained using the rigid-plastic approach showed reasonably good agreement with experimental test data, the scope of the analysis approach is considered limited. In this study, a validated finite element method, using the ABAQUS program, was employed to improve the rigid-plastic model, covering a broader spectrum of designs for axially-loaded TW3S walls. The reliability of the modified model was confirmed through comparisons with the available test data.

J. H. Doh, N. M. Ho, T. Peters
Flexural Capacity Accounting for SBHS500 Steel of Composite Bridge Girders

The positive bending moment capacity of composite steel girders is examined through study employing elasto-plastic FE analyses. The web slenderness limits of section classification for homogeneous and hybrid girders with bridge high performance steel are explored. Besides, the effects of initial bending moment due to unshored construction method on the web slenderness limit are investigated. It is shown that the noncompact web slenderness limits in conventional design standards are conservative for composite sections.

Dang Viet Duc, Yoshiaki Okui
The Inadequacies of the Existing Structural Health Monitoring Systems for Cable Stayed Bridges in Vietnam

Since 2000 when the My Thuan Bridge, the first cable-stayed bridge in Vietnam, was put into operation, and now Vietnam has more than 20 types of cable-stayed bridges. Therefore, the Structural health monitoring (SHM) system is gradually being designed and installed for cable stayed bridges to ensure eco-nomic exploitation and safety. Due to the limited of financing sources, these systems are very limited, and their quality have a lot to be desired. Also, due to the lack of appropriate classification personnel with experience in the SHM system, these systems encountered a lot of problems. In this article author will deeply analyze the mistakes and problems of these SHM systems to find solutions for the future.

Luong Minh Chinh
Riding Comfort Assessment of High-Speed Trains Based on Vibration Analysis

This paper proposes a method to assess riding comfort of high-speed multi-car trains and railway systems by using three-dimensional train-bridge interactive models. Each train car is modeled as a multi-axle double-layer of mass-spring-damper system having 27 degrees of freedom and the bridge modeling is adaptive to various finite elements. The case study considers a real train of fifteen cars travelling at a speed range of 50-400 km/h over a railway section having a bridge and rail irregularities of U.S. Federal Railroad Administration class 6. The riding comfort of each train car is found to reduce considerably when it is crossing the bridge. The car body accelerations and bridge deflection are compared with the allowable values specified in the design codes for high-speed railways in Korea, Japan and Taiwan. The assessment shows that riding comfort of the considered railway section is poor and that the design of the railway section or the car body suspensions need to be revisited.

Van Nguyen Dinh, Ki-Du Kim, Dinh Tuan Hai
Assessment of Methods of Riprap Size Selections as Scour Countermeasures at Bridge Abutments and Approach Embankments

In flood season, abutment scour is one of the main causes of bridge damages or even bridge collapse resulting in the interruption of traffic and possibility death. The most commonly employed method of protecting bridge abutments against scour is the application of bank-armoring method. Riprap is the most common armoring scour protection method used at bridge abutments and approach embankment. The selection of riprap size is based on the assumption of riprap layer failure mechanisms. Despite the widespread use of riprap protection in Vietnam, the guidelines for its design at bridge abutments and approach embankment are based on limited research. This article presents assessment of methods of riprap size selections as scour countermeasures at bridge abutments and approach embankments and procedure of design guidelines for their uses.

Huy Quang Mai, Noi Thi Doan
A Review on Protection Methods Against Debris Accumulation for Bridge in Mountain Areas

In the mountainous region of Vietnam, in the flood season, the phenomenon of debris is very common, causing danger to bridges. Debris affects the scour morphology at bridge piers, thus increasing the bridge failure potential. During the flood in October 2017, the Thia Bridge collapsed in Yen Bai, Vietnam. After the survey, the large trees attached to the piers are believed to be the main cause of this bridge collapse. Debris accumulation countermeasures can be classified into two main categories, including structural and non-structural methods. So, this paper presents details of these methods, and their applicability in Vietnam.

Huy Quang Mai, Phong Dang Nguyen
Numerical modeling of thermo-mechanical performance of small-scale CFRP reinforced concrete specimen using near surface mounted reinforcement method

Carbon fiber reinforced polymer (CFRP) is commonly used in civil engineering in strengthening concrete structure such as slabs, beams, and columns using externally bonding reinforcement method (EBR) or near surface mounted method (NSM. Under thermo-mechanical condition that is close to fire case condition, CFRP reinforced structures are under actions of mechanical load and elevated temperature at the same time. In the literature, the evaluation of the thermo-mechanical performance (such as fire performance) of CFRP-reinforced concrete structures requires complicated-and-expensive experimental works on full scale or large scale structures and therefore this may exceed time limit and financial budget for multi-variables observation. This paper introduces a hybrid method (numerical based and experimental validated method) to evaluate the fire performance of CFRP reinforced concrete structure over a small scale laminate-CFRP reinforced concrete specimen which is then capable to evaluate fire performance of more general CFRP reinforced concrete structures.

Phi Long Nguyen, Xuan Hong Vu, Emmanuel Ferrier
Experimental characterization of multi-full-culm bamboo to steel connections

The present research examines the performance of newly developed multi-full-culm bamboo to steel connections under monotonic axial loading. The culms are of Kao Jue (Bambusa pervariabilis) bamboo species. Findings reveal that the plain (unreinforced) connections fail early by undesirable brittle longitudinal splitting of bamboo culms. The confinement provided by hose-clamps inhibits this brittle failure mode, and with sufficient end-lengths, drastically increases the strength and ductility of the connection. Compared to the hollow-section connections with hose clamps, adding mortar infill further increases the strength. However, it also restricts bolt-deformation and thus diminishes the ductility. More importantly, the European Yield Model (which refers to dowelled timber connections) can analytically estimate the obtained experimental yield loads with satisfying accuracy. This is a promising direction towards a more rational and safer structural design of bamboo structures.

Nischal P. N. Pradhan, Themelina S. Paraskeva, Elias G. Dimitrakopoulos
FE modelling of RC frames with Link Column Frame System under in-plane loading

The purpose of the link column frame is to provide acceptable collapse prevention performance and also easily repaired following a moderate earthquake. Linked column frame system (LCF) for steel structures was proposed by Peter Dusicka (2009) with the objective of utilizing replaceable components that are strategically placed to protect the gravity load carrying system. In this paper the concept is extended to Reinforced concrete structures. The analytical studies were presented in this paper mainly focuses on the behavior of normal and link column RC frames with different connection configurations. Quasi-static cyclic load analytical results are presented and discussed for three 1:3 scaled RC frames with and without link column. Link column with various connections between the main beam and the link column i.e. rigid and hinged connection as per IS 12303-1987. With respect to experimental results, by using ANSYS software, the finite element model related to these frames is made and calibrated, and then analysis under cyclic static loading are performed. The test results showed a significant increase in the energy dissipation with a decrease in relative storey drifts for the link column frames with hinged connection. Greater amounts of energy were dissipated by the link column frame which has a hinge connection designed according to IS 12303-1987.

J. Joel Shelton, G. Hemalatha, V. Venkatesh
Mechanical Behaviour of Four-Leg Base Configuration on Cold-Formed Steel Lattice Column

Steel lattice structure has often been used as column or girder, which is connected to each other by bolting, screwing or welding. Steel lattice is normally made using hot-rolled steel (HRS) and rarely used cold-formed steel (CFS). CFS is becoming popular in the building and construction sector due to less maintenance cost and ease of fabrication. The stability of the steel lattice structure either by using HRS or CFS is necessary to be studied and investigated, which is by checking their mechanical behaviour for the overall structure and focusing on the base configuration. The CFS lattice structure, member section, configuration, connection or fastener, end support and span must be checked to determine the mechanical behaviour. However, the failure of CFS, such as buckling, must be revised to ensure that the CFS lattice column is stable. The effect of CFS lattice structure mainly fails or become unstable due to the slender section of the structure, especially on the compression member. The slender section of the structure must be intentionally replaced with a short section or get added by bracing. There are four types of four-leg base configuration that have been tested. From the testing, the B.CFS 4 specimen showed the highest value of ultimate load among the specimens.

Mohd Syahrul Hisyam Mohd Sani, Fadhluhartini Muftah
Finite Element Simulation of Member Buckling of Cold-rolled Aluminium Alloy 5052 Channel Columns

This paper presents the numerical investigation of cold-rolled channel columns made of 5052 aluminium alloy subjected to member buckling. A detailed Finite Element (FE) model using software ABAQUS v 6.14 was developed to simulate an experimental program recently performed at the University of Sydney. In the FE simulations, actual measured properties and geometric imperfections were incorporated into the FE models. The FE results are compared and validated against the experimental results. These accurate and reliable FE models will be used for the future parametric study to extend the data range for the development of the design guidelines for the cold-rolled aluminium alloy channel columns subjected to member buckling.

Ngoc Hieu Pham, Cao Hung Pham, Kim J. R. Rasmussen
Lateral Buckling Tests of Cold-rolled Aluminium Alloy 5052 Zee Beams

This paper presents a series of four-point bending tests of cold-rolled aluminium alloy 5052 Zee beams subjected to lateral buckling. Six Zee beams with three different lengths were selected for testing. A dual-actuator loading system was specifically designed to keep the load always in vertical direction and through the shear centre of the cross sections during testing. Lateral buckling failure modes were observed in long beams, while local-lateral interaction buckling was seen in short ones. The test results in this study will be used to calibrate the new proposed design guidelines for cold-rolled sections subjected to lateral buckling in an ongoing research project at the University of Sydney.

Ngoc Hieu Pham, Cao Hung Pham, Kim J. R. Rasmussen
Elastic Buckling Solution for Perforated Thin-walled Channel Sections in Shear with an Aspect Ratio of 2.0

Thin-walled channel members subjected to shear are commonly perforated with web openings to provide access for building service systems. The changes in the stress distribution due to the presence of holes can cause the changes in the critical buckling load and the overall strength of the perforated members in shear. Recent research by S.H. Pham has provided buckling solutions based on Finite Element Method for determining the shear buckling loads of channel sections with web holes with shear aspect ratio up to 2.0. However, the research only focused on square and circular holes. With the same methodology, this paper provides a buckling solution for perforated channel members with elongated web holes in shear. FE models were constructed to generate the elastic buckling loads with a very wide range of hole dimensions. The assumptions about the stress distribution from the previous studies were also utilized in this study. A dimensional transformation is also proposed in this paper.

Duy Khanh Pham, Cao Hung Pham, Gregory J. Hancock
The Behaviour of Cold-formed Channel Sections with Elongated Web Holes in Shear

Cold-formed C-sections perforated with circular and square web openings in shear have been studied thoroughly. However, the web holes are likely to be elongated along the span length due to limited web depth to allow more access for building services in practice. This paper summarizes an experimental study on channels in shear with elongated web holes. The study uses a dual actuator test rig with the aim of minimizing the effects of bending moments at the two ends of the shear span and obtaining the pure shear capacity with an aspect ratio up to 2.0. A comparison of Direct Strength Method design loads for shear with the test results is conducted. The shear yield loads based on the previous proposals for the DSM in shear for perforated channels with square and circular web holes are used in this paper to assess the applicability of those proposals to the cases of elongated web openings.

Duy Khanh Pham, Cao Hung Pham, Song Hong Pham, Gregory J. Hancock
Experimental Investigation of Cold-Rolled Aluminium Alloy 5052 Columns Subjected to Distortional Buckling

The behaviour and strength of cold-formed columns are mainly influenced by local, distortional and global buckling or coupled instability phenomena. Distortional buckling may govern the column strengths of open cold-formed sections with intermediate lengths. The objective of this paper is to investigate the distortional mode and ultimate capacity of cold-rolled aluminium channel sections in compression. A total of nine columns with three different cross-sectional geometries were performed at the University of Sydney. These commercially available cross-sections were fabricated by using the cold-rolling process instead of extrusion. The geometric imperfections of channel specimens were measured using a specially designed measuring rig. Tensile coupon tests were also conducted from the flat portions and the corner regions of the cross-sections to determine the material properties. The specimens were tested in axial compression between two fixed ends. The ultimate loads and observed failure modes in the column tests are reported.

Le Anh Thi Huynh, Cao Hung Pham, Kim J. R. Rasmussen
Numerical Simulation of Cold-Rolled Aluminium Alloy 5052 Columns Subjected to Distortional Buckling

This paper describes Finite Element (FE) analyses of cold-rolled aluminium alloy 5052-H26 columns subjected to distortional buckling using the program ABAQUS. The results of distortional buckling tests in an experimental program performed at the University of Sydney are fully described in a companion paper. The simulation results are compared and validated against the distortional buckling tests. In detailed FE models, effects of such input parameters as mechanical properties of flat and corner areas and initial geometric imperfections are considered. The FE ultimate strengths are in good agreement with the experimental results. Therefore, the FE analysis can be used to predict the ultimate loads of cold-rolled aluminium alloy members including the post-buckling behaviour of thin-walled aluminium sections in compression subjected to distortional buckling. It is indicated that the reliable FE models in this study can be used to extend data range for future calibration of distortional buckling strength curve for design of cold-rolled aluminium columns.

Le Anh Thi Huynh, Cao Hung Pham, Kim J. R. Rasmussen
Use of Kriging metamodels for seismic fragility analysis of structures

In civil engineering, a seismic fragility curve is popularly used to predict failure probability of structures under different earthquakes, and hence propose essential rehabilitation strategies through risk assessment for future earthquakes. The curve shows the failure probability as a function of seismic intensity, e.g., spectral acceleration at fundamental frequencies of structures (Sa, T1), and can be obtained using one of three approaches: engineering judgment, empirical studies or numerical simulations. The paper focuses on constructing seismic fragility curves using numerical simulations, where robust approaches of seismic reliability analysis are based on direct Monte Carlo simulation technique. The MCS based method usually requires a relatively large number of simulations to obtain a sufficiently reliable estimate of the fragility. It therefore becomes computationally expensive and time consuming as generating the simulations using the actual model or called full model of the structure. In this regard, this paper suggests using Kriging metamodel as a viable alternative of the actual model to reduce computational costs in seismic fragility computation. The Kriging metamodel is constructed based on the training samples of input and corresponding output responses of the structure. The validation of this method is performed on two numerical examples.

Cong-Thuat Dang, Thanh Tran, Duy-My Nguyen, My Pham, Thien-Phu Le
Application of weighted Latin hypercube sampling in stochastic modelling of shear strength of RC beams

Stochastic modelling and probabilistic analysis of concrete members are very time-demanding, especially for nonlinear finite element analysis of concrete structures. This paper presents an application of weighted Latin hypercube sampling method in stochastic modelling of shear strength of reinforced concrete beams, which takes into account the sensitivity factors regarding the behaviour of the considered system. The results show with only a few simulations the statistical values of the load-bearing capacities of concrete structures can be determined with high accuracy if weighted Latin hypercube sampling is used.

Ngoc Linh Tran, Khuong Le-Nguyen
Predicting onset and orientation of localisation bands using a cohesive-frictional model

In this study, a localisation band idealised as zero-thickness surface and represented by a cohesive-frictional model is directly incorporated into the structure of a new constitutive modelling approach and is activated once a stress-based condition is met. The embedded cohesive-frictional model provides a natural way to detect both the onset and orientation of localisation bands. This is different from existing continuum approaches based on the loss of positiveness of the determinant of the acoustic tensor. The formulation in this approach also creates a strong link between quantities describing the localisation band in the model and experiments, facilitating the calibration of model parameters.

Linh A. Le, Giang D. Nguyen, Ha H. Bui
Non-linear deformational analysis of reinforced concrete frame

The paper presents the algorithm and some results of deformational non-linear analysis of reinforced concrete frame system taking into consideration of nonlinearity of materials. The nonlinearity of materials means the use of nonlinear models of concrete and reinforcement, stress-strain relationships of concrete and reinforcement are taken according to diagrams illustrated in Russian codes. The algorithm of deformational non-linear analysis has two stages. In the first stage, the relationship between element cross-sectional stiffness and internal forces was established. In the second stage, the structural analysis software SAP2000 was used for calculation of internal forces with the results received in the first stage. The results were investigated with a gradual increase of load values according to the relationship between element cross-sectional stiffness and internal forces. This helps to observe the places of formation of plastic hinges. From there some comments and recommendations were proposed to evaluate the criterion of limit state in structural analysis.

Tran Thi Thuy Van, Vu Thi Bich Quyen
Reliability Evaluation of Eurocode 4 for Concrete-Filled Steel Tubular Columns

This paper evaluates the reliability of the design provisions given in Eurocode 4 (EC4) for concrete-filled steel tubular (CFST) columns under axial compression. The evaluation is based on the experimental results of 2,224 tests on short and slender CFST columns (1,245 circular sections and 979 rectangular sections). Monte Carlo simulation is used to estimate probability of failure and the reliability index based on the randomness in dead and live loads, steel yield stress, concrete compressive strength and the error of the EC4 resistance model. The evaluation is carried out for both specimens within and beyond code limits of material strengths and section slenderness. The results of parametric studies indicate that the reliability index of EC4 is in the range from 2.3 to 4.2 which is quite below the target reliability value of 3.8 prescribed by EC4.

Huu-Tai Thai, Son Thai

Sustainable Construction Materials and Technologies

Preparation of low cement ultra-high performance concrete

Technology advancement in concrete industry and expanding interest for high quality construction materials have prompted the development of ultra-high performance concrete (UHPC). Despite of many advantages gained using this performance-based concrete, however, conventional UHPC recipe raises many concerns especially on sustainability issues. Producing UHPC, requires relatively high amount of cement content and often the compositions are not optimized. Low cement UHPC was proposed to minimize the economic and environmental disadvantages of current UHPC by incorporating high content of supplementary cementing materials (SCM). An experimental program was carried out to evaluate the effect of SCM combinations on workability and compressive strength. It was found that good consistency and highest strength of low cement UHPC could be achieved with binary combination of fly ash and ultrafine calcium carbonate as SCM replacing up to 50% of cement. Enhancement of compressive strength as early as 7 days at 12.5% followed by 8% at 28 days and 20% at 90 days were observed in this low cement UHPC.

Norzaireen Mohd Azmee, Nasir Shafiq
Matrix dependent piezoresistivity responses of high performance fiber-reinforced concretes

An experiment was conducted to investigate the matrix dependent piezoresistivity responses of high performance fiber-reinforced concretes (HPFRCs) under direct tension. Three comparative HPFRCs were produced from following matrice: M1 was the controlled matrix while amount of cement in M2 or M3 was partly replaced by CB or GGBS, respectively. All HPFRCs contained same amount of twisted steel fibers 2% volume fraction. The investigated HPFRCs exhibited strain-hardening and both self strain-sensing and self damage-sensing abilities. The replacement of cement by CB and GGBS produced high enhancements of first-cracking strengths but great reductions of gauge factors within first-cracking points. Besides, as CB and GGBS were used in M2 and M3, respectively, there were not clear effects on post-cracking strengths but slight enhancements of gauge factors within post-cracking points were observed.

Duy-Liem Nguyen, Thi-Bich-Nga Vu, Huynh-Tan-Tai Nguyen, Van-Ben Nguyen
Influence of elastic modulus under uniaxial tension and compression on the first-cracking flexural properties of UHPFRCs

This paper investigated the influence of elastic modulus under uniaxial tension and compression on the first-cracking flexural properties of ultra-high-performance fiber-reinforced concretes (UHPFRCs). The elastic modulus of a uniaxial stress versus strain response curves is defined as the slope of linear portion within the first crack and it refers to the stiffness of the tested material. Unlike metal exhibiting same elastic modulus in both tension and compression, the elastic modulus of UHPFRCs, observed from experimental tests in previous studies, were considerably different, and, they much influenced on the first-cracking flexural resistances from sectional analysis. Relationships between compressive strength and elastic modulus of UHPFRCs were also investigated and discussed.

Duy-Liem Nguyen, Minh-Thuan Duong
Investigation on shear resistances of short beams using HPFRC composited normal concrete

This paper presents an investigation on shear resistances of short beams using high performance fiber-reinforced concrete (HPFRC) composited normal concrete (NC). Total twelve short beams with identical span-length/depth ratio of 2 were tested under three-point bending. HPFRC and NC had their compressive strength of 80 MPa and 20 MPa, respectively. HPFRC layer was placed in extreme top or bottom fiber with various thicknesses; for each thickness, steel reinforcing-bar and no reinforcing-bar embedded inside beams were examined. The results of experimental test were evaluated and discussed.

Duy-Liem Nguyen, Van-Toi Do, Minh-Phung Tran, Luu Mai
Application of Fluidized Power Coating for Propellers

Fluidized bed powder coating is a process where a pre-heated part is dipped into a tank of fluidized thermoplastic powder, which is typically PVC or nylon. This work creates a beautiful and durable conformal coating for the surface of metal parts, machinery and equipment with a plastic film to protect against corrosion and environmental effect. In the shipbuilding industry, the fluidized bed powder coating method has been applied to the interior details, shell machinery and marine equipment. However, the application to the surface of the propeller has not been popular. This paper presents a study on the applicability of fluidized bed powder coating to surfaces of propeller. The authors have conducted research and experiments for a three-blade ship propeller. Research has compared the performance of the initial propeller and itself after applying the fluidized bed powder coating method. From research study result, the authors make an assessment and recommendations for the application of fluidized bed powder coating to propeller blade surfaces in shipbuilding.

Tuan Phan Anh, Huong Pham Thi Thanh
Design of a Drinking Water Disinfection Systems using Ultraviolet Irradiation and Electrolysis Cell

In this paper, the authors develop a concept design of a safety drinking water disinfection system powered by wind energy. The idea for carrying this study is to develop a safety Drinking Water Disinfection System (DWDS) for rural/island/mountain and removed areas in Vietnam as such as in ASEAN developing countries where the national electric grids may be lacked. The drinking water disinfection will use electricity from a small wind turbine. The study will focus to develop two main parts: development an energy-efficient UV treatment technology as main disinfection step with a small-scale electrolysis cell and development a small wind turbines for supporting the electric to the UV treatment and electrolysis cell. A prototype product of the safety drinking water disinfection powered by wind energy was created.

Tuan Phan Anh, Tan Nguyen Minh
The effect of mineral admixture on the properties of the binder towards using in making pervious concrete

Pervious concrete has not been much studied and applied in Vietnam, the outstanding feature of this concrete is the open pore system for water flowing through. The two most important indicators for evaluating the quality of pervious concretes are the permeability coefficient and compressive strength but these are two opposite functions. Research into the properties of this type of concrete, such as workability, strength, etc … is one of the most effective measures that will improve the quality of the binders. The purpose of this article is to improve the characteristic of binder by separately using silicafume (SF) and fly ash (FA) with a content of 10%; 20% and 30% and by using the combination compound of 10% SF with 10-30% FA. The two typical properties of binders are: the viscosity of the binders through the flowing time of Marsh cone, the instantaneous viscosity determined by the SV-10 viscosimeter and the cstrength of the binders.

Nguyen Van Dong, Pham Huu Hanh, Nguyen Van Tuan, Phan Quang Minh, Nguyen Viet Phuong
Horizontal response of base-isolated buildings supported to high damping rubber bearings

Seismic isolation is one of the most efficient techniques to protect structures against earthquakes. Rubber bearings are suitable for low-rise and medium-rise buildings due to its durability and easy fabrication. This paper presents the horizontal response of a six-storey base-isolated building using high damping rubber bearings (HDRBs) under two ground motions of earthquakes as types I and II in JRA (2002) by finite element analysis. In this analysis, these bearings are modelled by the bilinear hysteretic model which is indicated in JRA and AASHTO. Comparison of horizontal response including base shear force and roof level acceleration between the two cases: base-isolated building and fixed-base building is carried out to evaluate the effectiveness of the use of HDRBs on the protection of buildings from earthquakes. The numerical results show that the peak value of roof floor acceleration of the fixed-base building is two times higher than that of the base-isolated building, and the floor accelerations depend on the peak values of ground acceleration. In addition, the step-by-step design procedure for determining the size of HDRBs used for buildings is also presented in this paper.

Nguyen Anh Dung, Le Trung Phong, Tran Minh
A Study on Behavior of Reinforcement Concrete Beam using the Recycled Concrete

The demand for concrete materials in construction becomes huge due to the development of the economy and urbanization in Vietnam. Recently, recycled aggregate concrete has been studied for partly replacing natural stone of concrete in the worldwide. It could save cost for land filling, and con-serve the national resources such as river sand and aggregate. Recycling concrete gives the benefit for environment. However, it may affect to the strength and performance of the construction containing the concrete waste. The paper is a discussion based on the experiments of reinforcement concrete beams with and without recycled concrete. Testing results are simulated by the ATENA program on exploring the behavior of beams. The analysis and experiment results show that replacing 20% of natural stone with re-cycled aggregate concrete does not affect both the bearing capacity and performance of beams.

Anh-Thang Le, Thanh-Hung Nguyen, Cong-Vu-Duc Phan
Geochemical modelling for prediction of chloride diffusion in concrete exposed to seawater

Steel corrosion is one of major problems that affect the durability of reinforced concrete structures. Chloride concentration is the key parameter for the steel corrosion risk of reinforced concrete exposed to seawater. Therefore, the durability of reinforced concrete can be evaluated by the prediction of chloride concentration into the reinforced concrete. Numerous numerical models have been developed to predict the chloride concentration in concrete however these numerical models have not yet fully simulated the nature of the chemo-physical processes taking place between the concrete and seawater. In this study, the prediction of chloride concentration is carried out by using the geochemical model including chemo-physical process. The geochemical model can improve the accuracy of the durability prediction of reinforced concrete. The accuracy of durability prediction is proved by the comparisons between modelled results and experiments results found in the literature.

Hoang Long Nguyen, Van Quan Tran, Long Khanh Nguyen, Tuan Anh Pham, Quoc Trinh Ngo, Van Loi Giap
Application of Asphalt Concrete using Limestone with Cement & Admixture

Vietnam is one of the countries in the world that will likely suffer from climate change predictions. The natural state of severe seasonal weather patterns in Vietnam, when combined with heavy trucks, makes the current conventional types of asphalt concrete are no longer able to bear the load. This results in common defects, such as rutting resistance and fatigue cracking of the current asphalt concrete roads surfaces. This article aims to introduce a type of high strength asphalt concrete using limestone filler, combined with cement and an adhesion additive that will help to solve the mentioned problem. The place of the pilot project was on a ten kilometers road (Km 1613+00 to Km 1623+00) on the National Highway number 1, which suffers from the heaviest traffic loads. The asphalt concrete was designed with a Marshall- Bailey Modification Method. After four years of use, the road was recently tested and remains in an operational and stable condition. There are many solutions proposed to apply the solution of high-intensity asphalt concrete using limestone filler combined with cement and admix. Wetfix®BE increased adhesive is the best solution due to the product’s cost-effectiveness, the availability of materials: like sand and stone. The asphalt concrete is high in strength, heat resistant, rutting resistance and fatigue cracking.

Nguyen Ba Hoang, Pham Van Hung, Tran Viet Khanh, Nguyen Viet Huy
Experimental Investigation of a Self-powered Magnetorheological Damper for Seismic Mitigation

The present work investigates the effectiveness of Magnetorheological Damper (MR) damper coupled with the smart self-powered system, MR damper acts as electromagnetic induction (EMI) device in controlling seismic vibration. The proposed smart damping system with an EMI device is capable of converting vibration energy into electrical energy. Thus, the EMI device attached with MR damper can be used as an effective and alternative power source for the MR damper, making it a self-powering system. The primary aim of the experimental study is to identify the performance of the proposed smart damping system using time history loading (El Centro earthquake). For experimentation, the MR damper with EMI was designed and fabricated. To reduce sedimentation, nano Fe3O4 was used in the preparation of MR fluid. The performances of the proposed smart damping system are compared with the passive, semi-active and active control system in force and displacement to evaluate the effectiveness of the self-powered smart damping system in reducing seismic vibration. The experimental results show that the self-powered smart damping system produces more damping force and reduction in displacement. The maximum damping force obtained is 0.67 kN. In an active system, a force was increased by 12.9% and displacement was reduced by 13.4% when compared with the semi-active control system. The results revealed that the proposed EMI can act as a sole power source for the damping system.

C Daniel, G. Hemalatha, L. Sarala, D. Tensing, S. Sundar Manoharan, Xian-Xu Bai
Effect of Ground Blast Furnace Slag in Replacement of Cement in Ternary Binder on Performance of Sand Concrete

With plentiful material resources including dune sand from Central Coastal provinces and fly ash – a by-product of burning coal at electronic power plants, sand concrete is widely used in Vietnam in respond to both technical and economical requirements. In this research, with the proportion of 18% cement, 37% crushed sand, 33% dune sand, and 12% fly ash, the length change in alkali-silica reaction and strength development tests were conducted in order to evaluate the effect of ground (granulated) blast furnace slag (GBFS) in replacement of cement in 0%, 20%, 30%, 40%, and 50%, respectively on performance of sand concrete. Besides, the relevant microstructural changes due to GBFS proportion and 02 different curing conditions were observed to support the assessment on potential alkali-silica reactions by conducting scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) and X-ray diffraction (XRD). As a result of these tests, it is confirmed that 30% GBFS in replacement of cement is suitable content in this sand concrete.

Thanh Sang Nguyen, Long Hai Chu
Experimental Study on Effect of Ground Granulated Blast Furnace Slag of Strength and Durability of Sand Concrete

Concrete used for building structures in the marine environment requires a high level of durability, and as such an effective method to improve the level is the use of ground granulated blast furnace slag (GGBFS). The paper presents an experimental study on the effect of the replacement cement by 20%, 30%, 40%, 50% GGBFS on workability, mechanical properties and durability of sand concrete (SC). The results show SC containing 20% GGBFS had the highest compressive strength, splitting tensile strength, elastic modulus and abrasion resistance. The lowest chloride penetration corresponded to SC containing 30% GGBFS.

Nguyen Thanh Sang, Nguyen Tan Khoa
Mechanical properties of fly ash based geopolymer concrete using only steel slag as aggregate

Geopolymer concrete (GPC) is a sustainable and eco-friendly construction material in which industrial byproducts containing Si and Al such as fly ash and slag are polymerized using an alkaline activating solution to create hardened binder or inorganic polymer cement. This study evaluated GPC mixtures using fly ash as a geopolymer binder and granular slag materials in place of natural coarse and fine aggregates. Three GPC mixtures were designed to achieve specified compressive strengths (f’c) of 25, 30, 35 MPa by varying (1) mass of fly ash between 482 to 507 kg/m3 of GPC, (2) the ratio (by mass) of alkali activating solution to fly ash (AAS/FA) between 0.4 and 0.48, and (3) the ratio (by mass) of sodium silicate (Na2SiO3) to sodium hydroxide solution (NaOH) (or SS/SH) between 2 and 3. The mixtures were prepared for testing in hardened conditions. The results showed that GPC specimens (air-cured) yielded good compressive strength (between 34.80 and 44.85 MPa), flexural strength (ranging from 4.50 to 5.91 MPa), elastic modulus (between 30.99 and 35.50 GPa). These properties are likely a result of the high strength of slag aggregates and a chemical reaction between steel slag aggregates and the geopolymer binder, improving the interfacial transition zone and GPC microstructure. This study suggests that slag aggregates can be used in place of natural aggregate materials to improve GPC’s mechanical properties with a conventional curing process for construction applications.

Dong Van Dao, Son Hoang Trinh
Effect of fly ash on the mechanical properties and drying shrinkage of the cement treated aggregate crushed stone

This paper presents the influence of fly ash on the mechanical properties and drying shrinkage of cement treated aggregate crushed stone (CTACS) mixture. The fly ash can replace 20-40% the weight of cement for the mixture of 4% CTACS, while it can supplement 3-9% the weight of aggregate crushed stone for both mixtures of 3% and 4% CTACS. Furthermore, the experimental findings indicated that the reduction in the compressive strength and the splitting tensile strength of CTACS was inversely proportional to the fly ash content replaced partially by the cement. However, the increase in the compressive strength and the splitting tensile strength of CTACS was directly proportional to the fly ash content. It was observed from the test results that the drying shrinkage of all mixtures was smaller than the control mixture without fly ash. The drying shrinkage of mixtures reduced inversely to the proportion of the fly ash content when 20-40% cement was replaced by the fly ash. When adding 3-9% fly ash, the 6% fly ash gave the smallest drying shrinkage.

Ho Van Quan, Nguyen Van Tuoi, Chau V. Nguyen
Strength of Granulated Blast Furnace Slag during Hydration Reaction Process

Granulated Blast Furnace Slag (GBFS) is a by-product of iron production process in which the molten slag from the blast furnace is cooled down rapidly by the highly pressurized water. In many counntries, GBFS has been widely used as a geo-material in civil works, meanwhile in Vietnam, due to the lack of technical standards and development, iron and steel slags including GBFS have not been used in construction. In this paper, firstly, typical properties and chemical content of Formosa GBFS (produced by Formosa Steel Plant in Ha Tinh province, Vietnam) were observed and it was shown that physico-mechanical properties and chemical components of Formosa GBFS are similar to those of GBFS produced in Japan which have been widely used in the port and habor works as alternative sands. Secondly, the hydraulic property and its effects on the unconfined compressive strength were then clarified for different GBFS samples and based on which, an estimation method of unconfined compressive strength was then developed.

Tran Thanh Nhan, Hiroshi Matsuda, Tran Xuan Thach, Nguyen Dai Vien, Ho Trung Thanh
Use of Coal Ash of Thermal Power Plant for Highway Embankment Construction

The highway embankment construction allows to consume a huge volume of coal ash up to hundreds of thousands of tons per km. However, this is a material with very different physical and chemical properties from traditional materials, which requires different design, construction and acceptance solutions.This article first presents the results of the laboratory experiments to evaluate and classify coal ash according to the AASHTO M145 and ASTM C618, TCVN 9436-2012 standards. These results help to define the composition, construction and acceptance solutions of the road bed made of ash in Vietnamese conditions. The proposed solutions have been experimented at a road section constructed in 2017 in Ha Nam with the large scale (100m of grade IV, 12m wide, 2.2m high, 960 tons of coal ash) and conduced to analytical results.

Tung Hoang, Viet Phuong Nguyen, Hong Nam Thai
Impact of the Porosity of Coarse Aggregates on the Structuration of the Paste-Aggregate Interface: Elementary Model Study

In the context of sustainable development for concrete production, local aggregates and recycled aggregates should be preferred but they can be porous and of lower quality. As a result, the compressive strength and the durability of concrete are adversely affected. In a preliminary understanding and with a view to accentuating phenomena occurring in the concrete, the Elementary Model (EM composed of paste and gravel, was studied. In this paper, the effect of Water Porosity (WP), moisture state and volume of coarse aggregates, as well as the nature of mineral admixture on the WP of EM was taken into account. Results indicated that volume and water porosity of aggregate are the two most important factors affecting WP of EM. Besides, it was also shown that aggregate porosity has the same trend of impact on the WP of EM while does not have the same trend of impact concerning the effect of the cement paste-aggregate interface on the WP of EM whatever the nature of mineral admixture, water porosity, moisture state and volume of aggregate. Explanatory attempts are proposed from the Scanning electron microscope (SEM) in combination with Energy dispersive spectroscopy (EDS) to support for statistic and ranking analysis.

Tran Duc Long, Cassagnabère Franck, Mouret Michel
Strength and Engineering Properties of Cementless Paste Produced by GGBFS and MgO

This study aims to investigate engineering properties of cementless pastes which were produced by reactive magnesium oxide (MgO) and ground granulated blast furnace slag (GGBFS). The mixtures were designed in various levels of MgO at 2.5%, 5%, 7.5%, 10%, 15% and 20% of total binder weight. The slump flow test, compressive strength test, ultrasonic pulse velocity test (UPV) and thermal conductivity test were conducted to examine the engineering properties of the pastes until 28 curing days. The results indicate that the high proportion of MgO causes the decrease of flow-ability of fresh pastes. Increasing MgO content significantly promotes the hydration process and improves the compressive strength and hardened properties of pastes through the UPV and thermal conductivity testing results.

Chao-Lung Hwang, Duy-Hai Vo, Khanh-Dung Tran Thi, Mitiku Damtie Yehualaw
A Non-paraffinic PCM Modified Textile Reinforced Concrete Sand-Wich Panel

There is growing interest in the use of phase change materials (PCMs) in the building industry, particularly in cementitious materials.In the present study, a modified mortar matrix with different amounts of PCM (5wt %, 10wt%, 15wt %) have been prepared. The different PCM-mortar matrixes have been mechanically characterized. It was found that PCM drastically decreases the mechanical performance of mortar.The 10% PCM-mortar matrix has been reinforced with 2 layers of AR glass Fabric and has been used as a skin of textile reinforced concrete (TRC) foamed sandwich panel.The performance of the 10% PCM modified TRC sandwich panel has been compared with a reference TRC sandwich panel (without PCM).It has been found that the mechanical performance of the PCM modified sandwich panel decreases comparing to the reference, however TRC ductile behaviour is conserved during bending which is very encouraging in view of developing a new sustainable TRC sandwich panels with high mechanical and thermal efficiency

Zakaria Ilyes Djamai, Amir Si Larbi, Ferdinando Salvatore
Design Method for Optimizing Geopolymer Concrete Proportions Utilising Entirely Steel Slag Aggregates

Fly ash and steel slag, which are byproducts from thermal power and steel plants respectively, have been used to manufacture geopolymer concrete (GPC). When combined, fly ash-based GPC using steel slag aggregate (GPCs) is effective in solving environmental concerns caused by the excess of byproducts. However, compared to Portland cement concrete (PCC), GPC is a newer material, and its mix design method to target a specified compressive strength has not been defined. To help make the GPCs mix design process more efficient, this paper discusses a statistical model that can be used to estimate the compressive strength of GPCs mixtures with 100 percent steel slag aggregates. The model was developed based on an experimental design in which the three variables were varied as follows: (1) the sodium solution (NaOH) concentration was varied between 10 and 14M, (2) the mass ratio of alkaline activation solution to fly ash (AAS/FA) was changed from 0.4 to 0.5, and (3) and the mass ratio of sodium silicate (Na2SiO3) to sodium hydroxide solution (SS/SH) was varied from 2 to 3. Results obtained in this study show that the model can reasonably estimate the compressive strength of GPCs mixtures based on the three variables, so it is recommended for use in GPCs mix design in the future.

Dong Van Dao, Son Hoang Trinh
Experimental Measurement and Modeling of the Complex Poisson’s Ratio of Bituminous Mixtures

A complete characterization of linear viscoelastic properties of bituminous mixtures requires the measurements of the complex Poisson’s ratio. The complex Poisson’s ratio of bituminous mixtures is not easy to obtain because of the high precision required and the limited accuracy of the experimental device. In this paper, three dimensional cyclic tension-compression tests were performed to measure the complex Poisson’s ratio. Two bituminous mixtures were tested: one prepared with classical bitumen and one prepared with polymer-modified-bitumen. In order to measure the complex modulus and the complex Poisson’s ratio, the sinusoidal loadings were applied on the specimens at different temperatures and frequencies. The experimental results show that the complex Poisson’s ratios of bituminous mixtures vary as a function of reduced frequency. The master curve of the complex Poisson’s ratio can be built using the same shift factor for the master curve of the complex modulus. It was verified that the Time-Temperature Superposition Principle and the Partial Time-Temperature Superposition Principle can be applicable for the complex Poisson’s ratio of the classical bituminous mixtures and the polymer-modified-bitumen mixtures, respectively. A linear viscoelastic model with a continuum spectrum called 2S2P1D is used to simulate the 3D linear viscoelastic behavior of tested bituminous mixtures.

Quang Tuan Nguyen, Thi Thanh Nhan Hoang
Evaluation of Macro-Synthetic Fibre Reinforced Concrete as a Sustainable Alternative for Railway Sleepers

Sleepers are among the most essential components within the track infrastructure and are characteristically made from timber, steel and prestressed concrete. However, due to recent concerns in regard to the inferior quality, degradation, durability, high-cost and environmental impact of the conventional materials, researchers are now focused towards sustainable alternatives such as composite materials. Correspondingly, even if these new sleepers provide the adequate strength characteristics towards the redistribution of high static and dynamic loads, their practical implementation remained fairly limited due to their unknown long-term behaviour and high production cost. This paper presents a review of the Macro-Synthetic Fibre Reinforced Concrete (MSFRC) sleepers which uses BarChip fibres towards the optimisation of the mechanical properties. In addition, the effects of different fibre dosages and aspect ratios will be thoroughly assessed. Further, the sustainability aspects of the MSFRC sleepers will be discussed with respect to durability and resource minimisation. As a result, the implementation of the recycled fibres within the concrete sections is expected to reduce the overall carbon-footprint of the sleeper towards a characteristically adequate and sustainable alternative material for railway sleeper applications.

Christophe Camille, Dayani Kahagala Hewage, Olivia Mirza, Fidelis Mashiri, Brendan Kirkland, Todd Clarke
The Repairing Effects of Lithium Silicate Based Material to the Surface of Hardened Concrete

There are many damage types on concrete structures. Crack and spalling on concrete structures are the most popular damages. The causes of these damage are variable but mostly originate from the corrosion of reinforcement that cause by the salty, humidity air, carbonation or ion chloride penetration via appeared cracks on the concrete surfaces that lead to the expansion of the reinforcement cross section. It is necessary to protect the surface area of concrete in order to prevent concrete structures from being deteriorated. The method of applying a surface protective agent has been developed as one of the methods to protect concrete. In this study, the repairing effects of lithium silicate based surface protective agent in high permeability and chloride resistance will be evaluate. As a result, reduction of coefficient of water permeability and effective diffusion coefficient of chloride ion of hardened concrete that had been repaired by the lithium silicate based surface protective agent were confirmed.

Nguyen Xuan Tung, Ryoma Kitagaki, Yoshiro Yamakita
Research on fabricating flowforms from ultra-high performance concrete with local admixtures for use in processing contaminated water

In the recent years, flowforms have emerged as an effective natural aeration solution to provide dissolved oxygen (DO) for treatment processes of contaminated water. Flowforms are usually made from materials such as: cement, concrete, ceramic, glass, composite stone, metals… Among which, concrete and ceramic are most common due to the low production cost of the former and relatively good durability of the later. However, plain concrete has some disadvantages such as: heavy weight, difficult maintenance and prone to corrosion of the surface, i.e. peeling of fine aggregates on the surface resulting in loss of smoothness needed, while ceramic surface can develop cracks over time. Recent studies on ultra-high performance concrete (UHPC) with admixtures available in Vietnam such as silica fume and fly ash showed that, with high workability, this material would satisfy well the requirements for fabrication of flowforms in terms of smooth surface, high mechanical durability, corrosive resistance of finish product. The research team has successfully fabricated flowforms prototype from UHPC and tested it in practice. The test results on waste water in two years showed that UHPC has a distinct advantage over the most common materials in flowforms fabrication: it preserves the smooth surface, unlike the etched surface of cement or cracked surface of glass enameled ceramic (tested in same condition). In addition, flowforms made from UHPC also has the advantage in production cost, compared to ceramic and a good potential in reuse of industrial wastes. This article will cover the process of fabricating flowforms from UHPC with silica fume and fly ash admixtures as well as the results of testing flowforms prototype in waste water treatment.

Thi Thuy Ha Ung, Tuan Hung Pham, Tho Bach Leu
Research on application of flowforms in combination with planted constructed wetland for improving water quality of urban polluted lakes

With continuously increasing urbanization in Vietnam, urban lakes pollution by domestic wastewater has become a serious issue, which results in degradation of lake water quality and consequent deterioration of landscape as well as environment for urban residents. Finding low-cost, simple and sustainable solutions would help to overcome that issue in Vietnam’s context. This study aims at proposing a solution which includes low-cost, nature- and landscape-friendly processes such as wetlands and flowforms for improving polluted urban lakes. The study was carried-out on a pilot system consisting of a cascade of flowforms and a planted constructed wetland with flow recirculation. Water samples used in this study have been collected from an urban lake in Hanoi, which receives wastewater from a densely populated residential area. The research results have demonstrated that this solution could achieve high treatment efficiencies: Color - 92%, Chemical oxygen demand (COD) - 92%, Ammonia (NH4+-N) - 98% and Total Phosphorus (TP) - 87%. The effluent quality could meet requirement by Vietnam’s National technical regulation on surface water quality QCVN 08-MT:2015/BTNMT, level B1 in terms of the above mentioned parameters.

Thi Thuy Ha Ung, Tuan Hung Pham, Tho Bach Leu, Thi Hien Hoa Tran, Hong Nhung Chu
A model of local kinetics of sorption to understand the water transport in bio-based materials

The classic models describing the hygric mass transfers inside porous materials seem unsuitable in the case of bio-based materials. They are based on the assumption of instantaneous local equilibrium between relative humidity and water content [1]. These two parameters evolve according to the diffusive fluxes following the sorption isotherms. This study shows that it leads to predict much shorter times of stabilization than those experimentally obtained. A new approach is presented here, it frees from the local instantaneous equilibrium introducing a local kinetics to describe the transformation of water from vapor state to liquid state and vice versa. The local kinetics of sorption is coupled with the well-known hysteresis phenomenon. It is adjusted from bibliographic data [2] giving mass evolution of three hemp concretes under adsorption / desorption conditions. 1D cylindrical simulations allows an excellent fitting on the experiments. Finally, a semi-empirical model is proposed, allowing to determine the kinetics parameters more easily. The effect of the local kinetics model on the hygrothermal transfers occurring through a bio-based wall is then studied.

N. Reuge, F. Collet, S. Pretot, S. Moissette, M. Bart, C. Lanos
Air permeability of cover concrete quality of precast box culverts affected by casting direction

Casting direction is an external factor that can influence the properties, including air permeability of concrete structures. In the current study, the effect of this factor on the air permeability of precast box culverts was investigated. The Torrent air permeability test was used to measure coefficient of air permeability kT for two box culvert specimens produced using ordinary Portland cement, water-to-binder ratio of 0.485, different casting directions (vertical and horizontal) at the age of 3 months. The obtained results show the different cover concrete qualities between the surfaces of the horizontal casting specimen, whereas the shortcomings during casting process were detected of the vertical casting specimen.

May Huu Nguyen, Kenichiro Nakarai, Saeko Kajita
Effects of Amounts and Moisture States of Clay-Brick Waste as Coarse Aggregate on Slump and Compressive Strength of Concrete

Effects of clay-brick waste (CBW) from demolition in construction on slump and compressive strength of concrete were investigated to promote the reuse of such waste at Vietnam for concrete technology towards sustainable development. The replacements of coarse aggregate by CBW were 0, 10, 20, and 40% by volume. To evaluate the effects of moisture states of CBW on properties of concrete, two states of CBW with a size range of 5–25 mm were prepared: (1) under oven-dry condition and (2) under saturated-surface dry condition. Results showed that the higher the replacement of CBW, the lower the slump of fresh concrete. The moisture states of CBW also affected slump of fresh concrete and compressive strength of hardened concrete. Although CBW under saturated-surface dry condition reduced the compressive strength at the age of 3 days, internal water released from CBW promoted the cement hydration after 3 days, leading to an increase in compressive strength of concrete at the ages of 7 and 28 days. Consequently, CBW can be reused as coarse aggregate for making concrete towards sustainable development of construction materials.

Phuong Trinh Bui, Xuan Nam Nguyen, My Ngoc Tang, Yuko Ogawa, Kenji Kawai
Investigation of the use of reclaimed asphalt pavement as aggregates in roller compacted concrete for road base pavement in Vietnam

When reinforcing existing asphalt pavement while the pavement elevation must be maintained, old surface asphalt layers are generally milled to apply the new ones. The use of the reclaimed asphalt pavement (RAP) recovered from road deconstruction is very important. It is an actual need due to the rise of asphalt cost and the lack of natural aggregates. It respects also sustainable development. On the other hand, pavement rutting is the most issue in Vietnam. In order to reduce this issue, it is necessary to find efficient solutions. Roller compacted concrete (RCC), with well-known advantages (simple, economical and high stiffness modulus), is found as a very promising technique. For these purposes, a science and technology project has been granted by the Ministry of Transport of Vietnam. It aims to investigate the use of RAP as aggregates in roller compacted concrete (RCC) for road base pavement. In this project, RAP from two different resources is selected and their characteristics are evaluated. They are then used for the RCC mix design with three different RAP contents (0, 40 and 80% in masse of aggregates) and two different cements (PCB30 and PC40). Specimens are fabricated in laboratory to determine traditional mechanical properties (compressive strength, tensile splitting strength and elastic modulus) according to their curing periods. The results on one RAP show that the studied mixes have potential performances and can be used for road base pavement. Finally, one mix has been chosen to be used for construction of a full-scale experimental pavement.

Thi Huong Giang Nguyen, Tien Dung Nguyen, Trung Hieu Tran, Van Dong Dao, Xuan Cay Bui, Mai Lan Nguyen
Comparison between Critical Path Method (CPM) and Last Planners System (LPS) for Planning and Scheduling METRO Rail Project of Ahmedabad

The purpose of this paper is to compare Critical Path Method (CPM) and Last Planner System (LPS) with respect to Planning and Scheduling of METRO Rail Project, Ahmedabad, Gujarat. Critical Path Method emphasises on updating the network for tracking the progress as well as to identify the delays. Last Planner System works on the weekly schedules prepared from the Master Plan and Look-ahead schedules to avoid the delays. One of the stretch from North-South Corridor was selected for the study from Vijaynagar to Usmanpura. The data such as activities, duration of activities, sequence and inter-relation of activities etc. were collected to prepare the network as well as weekly schedules. The network was updated and original network was compared with the updated one and the delays were spotted for the stretch selected. Weekly plans were also prepared for the selected stretch from the look-ahead schedule and Master Plan. PPC (Percent Plan Complete) were calculated to track the progress as per planned schedule. The data were collected by conducting interviews of various personnel and visual observations. Both the approaches (CPM and LPS) have been applied on the selected stretch by action research process. The delays were calculated and studied for both the methods and it was observed that Last Planner System is more appropriate to use for big infrastructure projects like this to avoid time-overrun and consecutive cost over-run. Resources can be well utilized with the Last Planner System, too. The type of this paper is a Case Study.

Viraj Parekh, Karan Asnani, Yashraj Bhatt, Rahul Mulchandani
Study and propose the size of cement concrete slabs for airport road surface in Vietnam conditions

Cement concrete slabs (CCS) for road pavement has many ad-vantages such as high Young modulus and long life expectancy, but this type of road pavement needs transverse joints (contraction joints, expansion joints and construction joints) that adversely affect the using process. Recently, many scientists have been studying solutions to increase the size (length and width) of cement concrete slabs in order to increase the smoothness of the road pavement and reduce the amount of raining water penetrating into joints. In this paper, the authors study and propose solutions to use reinforcement to reduce the amount of joints on cement concrete pavement which bring a better using process of this road pavement type.

Nguyen Duy Dong, Nguyen Vu Viet, Nguyen Quoc Van
Experimental study of the thermomechanical behavior of the carbon textile reinforced refractory concrete subjected to the constant load and temperature heating

The carbon textile reinforced refractory concrete is an alternative material to strengthen or reinforce the structure in an elevated temperature environment or usually subjected to fire. This composite is one perfect combination of carbon textile reinforcement which ensures high capacities (mechanical strength and stiffness) at elevated temperature, and refractory concrete matrix which ensures thermal protection and loading retransmission into textile reinforcement. The aim of this paper is to identify the rupture temperature and exposure duration of carbon TRC in thermomechanical condition. This paper presents original experimental results on carbon TRC specimens subjected to 5 applied force levels (from 10% to 75% in comparison with the maximal strength of this material at room temperature) and temperature increasing. As results, the studied carbon TRC specimen can exhibit up to the temperature of 670 °C in 23 minutes corresponding with an applied force level of 50%. The rupture temperature and exposure duration of carbon TRC decreased progressively with increasing of applied force level. In comparison with the experimental result on carbon textile specimen, the contribution of the refractory matrix as thermal protection was found and analyzed. The exposure duration of the carbon TRC in case of fire could be calculated thanks to the temperature heating curve according to the standard ISO – 834.

Manh Tien Tran, Xuan Hong Vu, Emmanuel Ferrier
A study on improvement of early - age strength of super sulfated cement using phosphogypsum

Supersulphated cement (SSC) is a newly developed non-burned cementitious material. It is a kind of environmentally-friendly cementitious material due to its energy-saving, low-carbon emission, and waste-utilization. Compared with ordinary Portland cement (PC), SSC has many advantages such as low hydration heat, excellent property of resistance to sulfate, using less clinker but more gypsum. However, the setting time of this binder is quite long, so the strength development is slow at early age. The aim of this paper is to improve the early-age strength for SSC binder samples with 30% Phosphogypsum, 60% ground-granulated blast-furnace slag, the rests are cement or lime and activator Na2SO4 with different content. The research results show that compressive strength at 3-day age can be improved almost twice. Microstructural analysis by infrared spectroscopy revealed that ettringite formed earlier in the case of using activators and improved the microstructure and strength at early age of the binder. However, the strength of the SSC at the later age was reduced when compared to the control sample without activator. The results also show that the optimum content of activator Na2SO4 for improving SSC strength at early age is 1%.

Nguyen Ngoc Lam
Effect of calcium sulfate type and dosage on early strength and porosity of self-leveling underlayments

In recent years, self-leveling underlayments (SLUs) are often used due to high flow ability and self-smoothing properties. Besides the strength, other characteristics of SLUs such as workability, rapid drying, rapid hardening, shrinkage compensation, etc… are required. This paper presents the effect of calcium sulfate type and dosage on early-age strength and porosity of SLUs based on ettringite binders. The raw materials used for making SLUs binders are calcium aluminate cement (CAC), Portland cement (PC) and calcium sulfate (C$Hx). Two types of calcium sulfates (hemihydrate and anhydrite) were used in this research. The ettringite formation is the reaction that controls the mechanical properties at early age of SLUs such as rapid hardening, early strength gain, etc. It was found that using hemihydrate in SLUs gives higher compressive strength than using anhydrite at the same content of calcium sulfate. On the other hand, the pore size of SLUs will decrease with increasing the amount of calcium sulfate in SLUs thanks to the higher amount of ettringite.

Nguyen Ngoc Lam, Elodie Prud’homme, Jean-François Georgin
Heat resistant mortar using Portland cement and waste clay bricks

The waste materials of clay bricks are usually come in different ways. Some are created in factories during and after the production process as a result of human mistakes, inappropriate materials, or a mistake in production process, some others are formed in transportation and distribution stage and finally a large part of waste materials are formed as a result of destroying buildings. The amount of waste materials may account to millions of tons annually. Recycling waste clay brick by incorporating them into building materials is a practical solution for pollution problem. The aim of this study is to investigate the use of waste brick as aggregates and as a partial replacement for Portland cement in the production of heat-resistant mortar, which is used for the potential fire structure, created by flammable materials stored or used in the building. This mortar is capable of working in the heat range of 800°C and 1000°C. Mechanical properties of mortar are based on the finding a suitable content of additives from waste brick used for binder and a reasonable aggregate gradation. The research results showed that the use of additives from waste brick in different proportions by weight (20-45%) for the cement increase heat resistance of the binder. In addition, aggregate particles from waste brick having sintered structure can be able to improve the thermal stability of mortar at high temperature.

Nguyen Ngoc Lam
Performance of Recycled Coarse Aggregate Concrete with Different Nylon Fiber Content

In the present study, the effect of nylon fiber (NF) on the permeability as well as the mechanical properties of concrete incorporating 100% recycled coarse aggregate (RA) was experimentally investigated. Concrete was produced by adding 0, 0.6 and 1.2 kg/m3 of NF and then cured in water for the pre-determined period. Measurements of compressive strengths, ultrasonic pulse velocity and total charge passed through concrete were carried out, and the corresponding test results were compared to those of concrete incorporating natural coarse aggregate (NA). Test results indicated that recycled coarse aggregate concrete (RAC) showed lower performance than natural coarse aggregate concrete (NAC) because of the adhered mortars in RA. However, it was obvious that the addition of NF in RAC mixtures was much effective in enhancing the performance of the concretes due to the crack bridging effect from NF. In particular, high content of NF (1.2 kg/m3) led to a beneficial effect on concrete properties compared to low content of NF (0.6 kg/m3) with respect to mechanical properties and permeability, especially for RAC mixtures.

Seungtae Lee, Youngkyu Chu, Sangwook Ha, Yong Kim, Jaehong Jeong
Air permeability coefficients of expansive concrete confined by rebars

Torrent air permeability tester has been widely used as one the most reliable non-destructive tests for evaluating the quality of the concrete cover. In this study, the Torrent tester was employed to evaluate the influence of rebar con-finement on the surface layer quality of expansive concrete. Blast furnace slag cement was used with the expansive agent to prepare two types of specimens with/without embedded rebars. The results comparing the variation of the measured air permeability at the ages of 28 and 56 days indicated that the con-crete cover confined by rebars obtained a better quality than that of the plain one without rebars.

Le Anh Van, Kenichiro Nakarai, Nguyen Huu May, Yasutaka Kubori, Toshikazu Matsuyama, Hajime Kawakane, Shintaro Tani
Application of Six Sigma on METRO Rail Construction Project

Six Sigma is a Quality Improvement Technique widely used in Man-ufacturing Industry. Application of Six Sigma is yet to be explored exhaustively in the field of Construction. This study explores the possibility of application of Six Sigma in METRO Rail Construction. This paper defines and analyses Con-struction Performance of Pier Construction in METRO Rail Project of Ahmed-abad using Six Sigma Technique. A stretch of 4 km from North-South Corridor is selected for the study from APMC to Shreyas. The data such as Work Break-down Structure, List of Activities, Time of Activities, Dependency of Activi-ties, Construction sequence etc. is collected and analysed using software Pri-mavera and Minitab. Process Capability Analysis is used to determine how well an actual process meets a set of specification limits in a scheduled plan. Data is represented and analysed by preparing different charts and graphs such as I – Chart, Moving Range Chart, Capability Histogram and Capability Plot. A com-parison was done between the actual works done at the site and the schedule planned for the progress to calculate the Sigma value. It is found from the result that the calculated Sigma value is near to the ultimate Sigma Level. This work provides valuable insights for the implementation of Six Sigma Technique in the Construction Industry. Six Sigma Technique can evaluate the quality of cur-rent construction activity and quantify the improvement goals so as to control succeeding critical activities for the project. Improvement in Quality of Con-struction can be observed at large extent with the application of Six Sigma Technique. Six Sigma Technique can be linked with Lean Principle.

Viraj Parekh, Kushal Solanki, Nishit Prajapati
Experimental investigation of loading rate effects on the shear capacity of reinforced concrete deep beams

Unlike slender RC beams, shear failure mechanism of RC deep beams is mainly governed by shear compression; a considerable amount of the load is carried by the compression struts of concrete. For this reason, when subjected to a long-term sustained load, the shear strength of RC deep beam could be reduced as the sustained load might have negative impacts on the compressive strength of concrete. The purpose of this study is to investigate the influence of sustained loads on the shear capacity of RC deep beams. In this experiment, different loading rates were chosen as an alternative method to clarify the effect of sustained loads. Two main different types of loading rate, a normal loading rate of 10 mm/hr and a very slow loading rate of 0.01 mm/hr, were applied. 100x320x1200 mm RC beams with a ratio of shear span to the effective depth a/d=1 were tested under two-point loading. The test results showed that under very slow loading rate, the ultimate shear capacity was moderately reduced.

La Vanny, Kenichiro Nakarai, Halwan Alfisa Saifullah, Asuka Mizobe
Fatigue characterization of conventional and high rutting resistance asphalt mixtures using the cyclic indirect tensile test

In this paper, the fatigue behaviour of several asphalt mixtures that are widely used in Vietnam such as the dense graded asphalt concrete (AC) produced with 60/70 pen bitumen and high rutting resistance asphalt mixtures (HRRA) are investigated using the cyclic indirect tensile (IDT) testing device equipped at Ho Chi Minh City University of Technology and Education (HCMUTE). Several level of stress magnitudes were applied to determine the characteristic fatigue line (CFL) of mixtures. The results show that the widely used power law of CFL is applicable for all investigated mixtures. Although the stiffness of the HRRA is twice that of conventional AC, its resistance to fatigue is much higher. The effect of strain magnitude on the stiffness of mixtures or the nonlinearity effect was also recognized. It was observed that the impact of binder type on the nonlinearity effect is insignificant compared to that due to the volumetric design of mixture.

H. T. Tai Nguyen, Anh Thang Le, Vu Tu Tran, Duy Liem Nguyen
Sustainable Measures to Achieve Better River-Crossing Access in the Rural Areas of Developing Countries

Due to financial and technical constraints of the governments of developing countries, rural road networks generally offer poor access. At stream-crossing sections on rural roads, in particular, access may be cut off during the rainy season because of high water flooding the bridge. Considering the socio-economic situation and limited resources in rural areas, the authors proposed to build road-stream crossings through community initiatives by mobilizing local resources. Since then, several projects have been conducted. In order to assess the practicability of improving access at road-stream crossings and the performance of constructed structures, this paper presents case studies on projects in which low-water bridges and vented fords were constructed. Then, we discuss the performance of the structure and application criteria for construction, either by the community themselves or in collaboration with local government and community. It is demonstrated that road-stream crossing construction through community initiatives provides better access to roadside communities and enhances feelings of ownership, such that locals feel responsible for performing continuous maintenance and bridge safety.

Yoshinori Fukubayashi, Makoto Kimura
Assessment of Design Guidelines for Fiber-Reinforced Polymer Shear Contribution of Prestressed Concrete Beams Strengthened by Fiber-Reinforced Polymer Sheets

This research is mainly focussed on statistical assessment and analysis of the accuracy of predicting the shear resistance of the fiber-reinforced polymer (FRP) sheets for prestressed concrete beams strengthened by FRP sheets presented in the current design guidelines. The evaluation of the current prediction models is based on a database of experimental results from the previous and current author’s research. The specifications of the beams are diverse and wide enough such as beam types (prestressed concrete beams using bonded tendons - BPC beams and unbounded tendons - UPC beams), cross-section shape, concrete strength, effective prestress stress, and shear span to depth ratio - a/d …. The results of the evaluation have shown that the formulas in recent design guidelines overestimated the shear contribution of FRP sheets for prestressed concrete beams.

Dien Ngoc Vo-Le, Chinh Ho-Huu, Long Nguyen-Minh
Development of Disaster Resilient and Sustainable University Framework: Case of Bandung Institute of Technology (ITB)

Indonesia is an archipelagic and seismic active country, home to 241 million people. It also has 3,276 higher education institutions (in 2017), with a total of more than 6.9 million students and more than 247 thousands of academic staffs. Following the Sendai Framework for Action (SFDRR 2015-2045), Sustainable Development Goals (2015-2030), the Association of Pacific Rim Universities (APRU) has declared that universities need to ensure the safety of students, faculties, staffs and assets during natural disaster, which led to the concept of Disaster Resilient University (DRU). Bandung Institute of Technology (ITB) is the oldest engineering higher education institution in Indonesia. Its main campus is located in Bandung city and home to about 21 thousand students and 2600 permanent faculties and staffs. Bandung is vulnerable to flood, rain storm, fire, earthquake, landslide and volcano. Since 2017 the Research Center for Disaster Mitigation (PPMB), working together with ITB Unit for Security, Safety, Health and Environment (K3L) is promoting the concept of Disaster Resilient University. The ultimate goal is that ITB to achieve a Disaster Resilient University status by 2025, through the achievement of the following objectives: strong partnerships within the campus community as well as with government, built-in awareness and safety culture in ITB, and improved resiliency by building capacity for reducing disaster risk, managing emergency, including continuity of operation. The activities consist of 4 phases with the following outputs : ITB DRU policy and action plan; organized campus resources, disaster risk assessment of ITB Campuses; annual emergency response exercises and drill; trained campus staffs and students in the emergency response and continuity of operation. The DRU best practices will be shared with other universities and higher education institutions in Indonesia.

Krishna Suryanto Pribad, Rahma Hanifa, Eliya Hanafi, Giovanni Pradipta
Experimental study on the valorization of poplar by-products in cement-based materials

An experimental investigation was undertaken to evaluate the potential use of poplar by-products in cement mortars. Two by-products from poplar processing were studied: sawdust (from sawing wood) and milled fiber (from wood waste obtained during cutting). The fibers and sawdust were incorporated into the mortars as a sand substitution with rates from 10 to 100%. The introduction of these poplar by-products has a significant on the composite properties in both fresh and hardened state. It was noted that the workability of the mixtures with the poplar wood varies with the substitution rate. Moreover, the increase in the amount of fibers or sawdust causes a continuous increase in the porosity of the material, which leads to a decrease in density. A significant decrease in the mechanical properties of bio-sourced mortars was noted, again related to the rate of fibers or sawdust introduced in mixtures. The high internal porosity of the wood particles and their low density can explain these lower mechanical strengths.

C. Djelal, J. Page, Y. Vanhove, H. Kada
Horizontal response of base-isolated buildings supported to high damping rubber bearings

Seismic isolation is one of the most efficient techniques to protect structures against earthquakes. Rubber bearings are suitable for low-rise and medium-rise buildings due to its durability and easy fabrication. This paper pre-sents the horizontal response of a six-storey base-isolated building using high damping rubber bearings (HDRBs) under two ground motions of earthquakes as types I and II in JRA (2002) by finite element analysis. In this analysis, these bearings are modelled by the bilinear hysteretic model which is indicated in JRA and AASHTO. Comparison of horizontal response including base shear force and roof level acceleration between the two cases: base-isolated building and fixed-base building is carried out to evaluate the effectiveness of the use of HDRBs on the protection of buildings from earthquakes. The numerical results show that the peak value of roof floor acceleration of the fixed-base building is two times higher than that of the base-isolated building, and the floor accelera-tions depend on the peak values of ground acceleration. In addition, the step-by-step design procedure for determining the size of HDRBs used for buildings is also presented in this paper.

Nguyen Anh Dung, Le Trung Phong, Tran Minh
Evaluating the change in the properties of bitumen during production, transport and construction of hot mix asphalt in the conditions of Vietnam

In Vietnam, the total time of production, transport and construction of hot mix asphalt (HMA) can last up to more than 10 hours depending on the distance from the asphalt plan to the construction site as well as the weather conditions at that site. As a result, the properties of the onsite compacted asphalt mixture may be far different from those obtained in the laboratory, giving rise to unreliable predicted service life of the pavement. This study aims to evaluate the change in the properties of bitumen during production, transport and construction of hot mix asphalt. To simulate these processes, a 60/70 pen bitumen was heated to 150 °C for 1h, 3h and 5h and stirred continuously to allows the interaction between bitumen and oxygen. Control samples were also prepared by maintaining the bitumen at high temperature but not allowing the bitumen to interact with oxygen. The properties of the conditioned samples were then evaluated using viscosity test, penetration and softening point test, and Superpave performance grading (PG) test. The results show that the properties of the control samples almost do not change while those of the aged samples vary significantly with an increase of ageing time. The more longtime the bitumen was exposed to high temperature and interaction with air, the more stiffness gained by the bitumen.

K. H. Quang Trinh, T. Nhan Tran, H. T. Tai Nguyen
Creep behavior and rutting resistance of asphalt pavements by experimental testing and Finite Element modelling

Asphalt pavement rutting is a major safety concern because it affects the handling of vehicles. Research into effectively predicting of asphalt pavement rutting is extremely necessary as it can help develop an optimal design of asphalt mixture against rutting. The primary objectives of this study are to develop numerical models to investigate the asphalt pavement rutting. Previous study’s experimental tests including triaxial repeated compression loading and wheel track testing were used to evaluate the visco-elasto-plastic behavior and rutting resistance of different pavement mixes. Based on the test results, sets of visco-elasto-plastic creep parameters for the asphalt pavement mixes were characterized and related to their rutting resistances. Numerical simulations using three-dimensional Finite Element models were developed to simulate both the triaxial compression and wheel track testing. A ‘strain hardening’ creep material model with the material parameters developed from experimental testing was employed in the Finite Element modelling to the time-dependent characteristics of the asphalt concrete pavements. The Finite Element results were validated against the experimental results to demonstrate that the Finite Element simulations can be used to effectively evaluate the rutting behavior of asphalt concrete pavements.

Van Bac Nguyen, Chau Phuong Ngo, Ngoc Bay Pham, Thanh Phong Nguyen, Van Phuc Le, Van Hung Nguyen
Influence of High Temperature on Non-Silicate Based Activated Blast Furnace Slag

The energy consumption and the greenhouse gases emission in order to manufacture Portland cement (PC) is very high. To find an alternative, the researchers initially replace the PC partially by Fly Ash. Later on, the researchers introduce a new binder which is being manufactured by the activation of ground granulated blast furnace slag (GGBFS). The paper presents the detail of the binder, manufactured by GGBFS and mild alkali as activator having the pH value of 10. The binder is manufactured by simple blending in which 85% is GGBFS, and 15% is the chemical activator. The test results of the alkali activated binder concrete (AABC) for compressive strength, splitting-tensile strength and flexural strength were found after exposure to elevated temperature 100 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C, 700 °C and 800 °C. It has been observed that these results of the AABC at elevated temperature were very much comparable with that of the ordinary Portland cement concrete (OPCC). The deterioration in strength starts from 200 °C onwards. No spalling of the alkali activated binder concrete (AABC) has been observed at elevated temperature even at 800 °C.

Virendra Kumar, Amit Kumar, B. K. Prasad
Influence of Linz Donawitz slag aggregates on strength development of concrete

This paper aims to present the feasibility of Linz-Donawitz (LD) slag as an alternative for traditional natural aggregates in concrete. The LD slag possesses good physical and mechanical properties as an aggregate and it has been incorporated in concrete as a replacement material for natural fine and coarse aggregates. Both the natural fine and coarse aggregates were partially replaced by LD slag aggregates at 20%, 40%, 60%, 80% and 100% respectively. Concrete of grade M35 was cast, cured and tested with standard specimens following Indian Standard codes to study its mechanical strengths. The test results of compressive strength of concrete with LD slag aggregates are presented in this paper. The results obtained, show that there is an increase in compressive strength of the various grades of concrete with an increase in percentage replacement of natural fine and coarse aggregates with LD slag aggregates.

Brajkishor Prasad, Virendra Kumar, Prince Singh
Investigation of the effect of γ irradiations on the mechanical and physico-chemical properties of cementitious materials: from the nanoscale to mortars’scale

Concrete is commonly used in nuclear construction for decades. Because low-dose γ irradiations may play an important role regarding the extension of service life of some structures and long term properties of waste storage galleries, in-depth studies are necessary. A multiscale experimental campaign on γ irradiated cementitious materials from mortars to pure phases (C-S-H) has been carried out and the main results are presented herein. Macroscopic mechanical losses were measured after exposure to a total dose around 250 kGy. They depend on the environmental and curing conditions. Viscoelastic properties were assessed using a novel method coupling indentation and 3D-imaging. The structural and mineralogical modifications at microscopic scale due to irradiations were determined using a combination of experimental techniques (Raman, TEM, indentation, MIP). It was found that C-S-H undergo nanoscale structural modifications depending on their Ca/Si ratio (silica chains polymerization or network disorganization) which are probably related to the observed macroscopic degradations.

Maxime Robira, Benoît Hilloulin, Ahmed Loukili, Gildas Potin, Xavier Bourbon, Abdessalam Abdelouas

Geotechnics for Environment and Energy

Evaluation of the At-Rest Lateral Earth Pressure Coefficient of Fibre Reinforced Load Transfer Platform and Columns Supported Embankments

The at-rest lateral earth pressure coefficient (K0) is an essential soil property in design of geotechnical problems, but investigating its influence on behaviour of embankments supported by load transfer platform and columns improved soft soils has remained very limited. In this study, numerical modelling of a novel ground improvement technique utilising fibre reinforced load transfer platform (FRLTP) and columns supported embankment founded on top of multilayers of soft soils is proposed and investigated by finite element analysis (FEA). This research aims to assess the influence of a new ground improvement technique using FRLTP on the embankment behaviour supported by columns in soft soils. Moreover, a numerical assessment by varying the K0 value of FRLTP is performed through an extensive parametric study to investigate the K0 influence on the behaviour of FRLTP and column-supported embankments over soft soils. Results of the numerical modelling show that the final settlement, the difference in settlement between columns and foundation soil, the lateral deformation can significantly be reduced by the insertion of FRLTP into a column-supported embankment system. The predicted results also indicate that the changes in the K0 value were found to have no notable effects on the embankment behaviour.

Cong Chi Dang, Liet Chi Dang
Nonlinear Behavior Analysis of SFRC Foundation Considering Homogeneous and Inhomogeneous Soil Interactions

Current structural design and analysis commonly use numerical simulation. Interactive problems often use this method to express the behavior of different types of structures when working together subject to external loads. This study shows the relationship between compression forces and displacements of a slab foundation that are directly interactive with inhomogeneous soil when using the stress-strain curve of steel fiber reinforced concrete material proposed by Barros and Figueiras [1]. The obtained results are better than the previous study of Vaskova and Čajka [3] when both experimental test results are compared. Otherwise, only using one type of element for both the foundation and the soil does not affect this interaction problem. The material model is an essential part of the simulation, and the problem should consider nonlinear behavior analysis.

Tran-Trung Nguyen, Radim Cajka, Phu-Cuong Nguyen, Thanh-Tuan Tran
Analyses on drainage capacity and sliding resistance of large diameter vertical wells for deep-seated landslide stabilization

Deep-seated landslides occurring near roads and building areas cause serious damages. High groundwater level due to long periods of rainfall or infiltration from reservoir saturates and softens soils landslides. This article introduces an approach which combines the restraining effects of stabilizing piles and the dewatering effect from large diameter vertical wells, to increase the stability of landslides. Effectiveness in resisting sliding force and lowering the groundwater level was evaluated using the finite-elements method. Our results show that the saturation line drops significantly, and the safety factor of the slope increases by approximately 20% compared to the case without the wells.

Ba Thao Vu, Van Minh Pham, Quoc Dung Nguyen, Huy Vuong Nguyen, Thi Thanh Huong Ngo
Shape effects in the dynamical response of flints/boulders during pile driving – a numerical study

Today, more than eighty percent of the total power of the active off-shore wind turbines is installed in Europe, where the offshore wind industry has gained full reliability and is now targeting to continue reducing the construction cost. About 20 to 30% of the cost of an installed turbine is the foundation, where installation plays a major role and thus cost reduction will be mostly impacted by developments. This paper presents the following of a study of the dynamic reaction offered by a flint to the pile tip, which was presented in the 2018 Hanoi Conference, taking into consideration a circular and elliptical shape and the possibility of a non-centered impact of the pile wall on the boulder/flint. The work is aimed at the exploration of the effect of the shape of the boulder/flint and concludes with a simple prediction method to reduce the risk of pile tip damage.

Emilio Nicolini, Ivan Terribile
The failure envelope of a new shaped cross-plates foundation for deep-water soft soils

The offshore deep-water oil&gas fields are very often facing the need of installing heavy structures on soft seabed soils, with complex loading acting on the foundations. Service structures which are installed to control the oil&gas production and flowlines like PLETS, ITA, seabed manifolds, are examples of such structures. Different types of foundations are today available for the deep-water seabed (mudmats, suction piles and anchors, etc.), which require a fit for purpose construction and thus are not well suited for automated installation. As it is believed that automated construction will be favourable to the necessary cost reduction of deepwater fields, a research in this direction has been activated. This paper will introduce the results of part of this research program aimed at the study of a new foundation concept, which is being developed within a wider project of automated deep-water foundation construction. Results that will be presented regard a further step of the optimisation study to find the best shape of a foundation formed by crossed plates inserted vertically in soft soils. Geotechnical verification of the resistance of the foundation will be presented in terms of shear and axial force failure envelopes obtained by numerical analyses. The optimisation process will take into account, additionally to the geotechnical performance, the structural compatibility.

Emilio Nicolini, Alessandro Alberio, Matteo Castelletti
Enhanced Oil Production in the lower Miocene reservoir by Multistage Fracturing, Offshore Viet Nam

Oil production has been declined in the fractured basement reservoir from these fields of the Cuu Long Basin as those reservoir pressures were highly decreased. To produce oil, those reservoirs from these fields have been stimulated by using various techniques for enhanced oil production. Water injection at secondary recovery to maintain the reservoir pressure has been flooded because this technique has still brought high efficiently oil production, but the high-water cut has been very challenged while producing oil from the reservoirs. The most efficient way to recover oil in the Cuu Long basin is to stimulate the lower Miocene reservoir by hydraulic fracturing. This study presents the effective multi-stage hydraulic fracturing in the lower Miocene reservoir for single X well of the Cuu Long basin on the continental shelf offshore Viet Nam. The calculated results of multistage fracturing show that the average effective wellbore radius, average pseudo-skin, average productivity ratio, fracture conductivity are higher than those of the blanket and un-stimulated case. The integrated model of multistage fracturing consists of fracture geometry, fracture parameters, conductivity and production model.

Huu Truong Nguyen, W. Bae, Van Hung Nguyen
Properties of geopolymer modified sludge generated in landslide area designed by Taguchi method

It has been claimed that heat treatment is necessary for the reaction of geopolymer to achieve the desired strength and form. However, it’s also the drawback affecting the application of Geopolymer in the construction site. There-fore, instead of heat treatment, the other important factors for synthesizing the geopolymer matrix in the soft soil environment, is the main focusing of this paper. The Taguchi method was used to determine the most important factor that affects several properties of geopolymer modified sludge by minimizing the effects of variation, but without eliminating the cause. The results indicate that the geopolymer content, clay content in sludge, initial water content and moisture content play a unique role in different properties of modified sludge.

Minh Chien Vu, Tomoaki Satomi, Hiroshi Takahashi
Granular flows through a model-scale forest: Influence of tree density and implications for landslide mitigation

Landslides pose a severe threat to the man-made and natural environment. As a result, many different artificial structures have been employed to attempt to mitigate the damage from these hazards. However, natural systems, such as forests of trees, can also play a defensive role by dissipating energy and reducing flow speed. This study uses a small-scale model forest to investigate the effectiveness of such sustainable measures. It examines how granular flows interact with arrays of tree structures at different densities, comparing the results to flow down a bare plane. Using image analysis of high-speed camera recordings, we track the lateral spread-out area and the speed of the flows. The results show that the trees have a strong decelerating effect in the downstream direction, and also slow the rate of lateral spread out. The knowledge gained from these experiments can be applied to the field scale, and could provide useful practical guidelines for alternative, sustainable hazard mitigation in mountainous areas.

H. T. Luong, J. Baker, I. Einav
Dynamic properties of loose sand using numerical analysis-A case at Hong Thai Tay coal transportation road project (Vietnam)

In this paper, a study was conducted to investigate the dynamic behaviors of loose sand collected from Hong Thai Tay coal transportation road project (Vietnam). Cyclic direct simple shear tests (CDSS) were performed on the soil using a finite element method program. The CDSS test was controlled under drained strain condition with the vertical effective consolidation stress of 100 kPa. In addition, the other dynamic control parameter, cyclic stress ratio, was subjected to vary in the range of 0.04-0.1. A total of 30 cyclic direct simple shear tests were performed with respect to the number of uniform cyclic cycle and cyclic stress ratio to determine the dynamic parameters of the sand plasticity model. Eventually, the dynamic properties of the investigated sand were ob-served through various dynamic aspects. As a result, the strain amplitude of the loose sand in this study slightly increased within the first fifteen-loading cycles. From the sixteenth cycle, huge increments were observed during the cyclic test. This result agreed well with that of excess pore water pressure ratio, that is, the development of excess pore water pressure reached about 1.0 after fifteen cycles of loading. Moreover, the obtained results of the shear modulus reduction ratio from this study were compared to those of sand from the literature reviews.

Nguyen Phi Hung, Nguyen Van Dung, Tan Do
Application of Box-Behnken Design in Optimization of Fracture Treatment Design for Lower Oligocene Reservoir, Offshore Viet Nam

The paper presents an approach for optimizing the design of hydraulic fracture treatment in the low permeability lower Oligocene sandstone reservoir in the Cuu Long Basin, offshore Viet Nam. Several design variables including low behavior index, leak-off coefficient, pumping time, injection rate and proppant, which are generally affecting the fracture mechanics, were considered in the optimization process in order to improve oil production. The influence of those variables and interaction variables on fracture conductivity and net present value (NPV), hence, the production performance was analyzed using Box-Behnken design–based statistical modeling, which are experimental designs for response surface methodology. The results show that the maximum NPV was 50.5 million USD from optimal variables including injection rate of 36bpm, injection time of 78 minutes, slurry concentration end of the job of 9.1ppg and the leak-off coefficient of 0.0034ft/min0.5.

Huu Truong Nguyen, W. Bae, Van Hung Nguyen
Experimental and numerical assessments of seepage effect on embankment behaviours by the time

The incidents of dam failure occur due to some different reasons, in which the reason for seepage accounts for 35%. The seepage leading to the dam incidents can be divided into piping, internal erosion, solution of soluble rock, excessive internal pressures and/or saturation and excessive uplift, heave, or blowout. Currently, empirical method is commonly used to study the influence of seepage on the dam incidents. This paper presents a research work on the development of the experimental equipment and procedure for evaluating seepage effects on several physical properties of embankment, which include cohesion, friction angle, density and permeability coefficient. The testing results provide important material inputs to the finite element model used for the stability analysis of the main dam of Ta Trach reservoir (Thua Thien Hue Province, Vietnam) caused by the seepage phenomenon.

Thanh Quang Nguyen, Truong Linh Chau, The Hung Nguyen
A numerical homogenized law using discrete element method for continuum modelling of boundary value problems

This paper presents a new way to define constitutive laws based on particles interactions within the Discrete Element Method (DEM). The concept is based on Volume Element (VE) for which the constitutive law is constructed through a numerical homogenization process. The new law fully accounts for the discrete nature of granular materials. By using the response envelope diagrams proposed by Gudehus [1], a graphical representation of the constitutive law is obtained. The results suggest that the current law can fully capture the main features of granular materials such as anisotropy, path dependence and non-linearity.

Trung Kien Nguyen, Jacques Desrues, Gaël Combe, Duc Hanh Nguyen
Influence of heterogeneous fractured fault damage zones on shear failure onset during fluid injection

Fault stability analysis is traditionally performed by assimilating fault systems to surfaces. Yet, faults are complex and heterogeneous geological systems, whose compartmentalized architecture generally corresponds to an inner core (FC) of small thickness (i.e. principal fault plane) surrounded by outer, often fractured damage zones (DZ). Depending on the fractures’ network characteristics, the latter compartment can be related to complex spatial distribution of hydro-poro-elastic properties, which can strongly influence the shear failure tendency of the fault zone during massive injection of fluid into reservoirs. Using the upscaled DZ properties derived from outcrop surveys at Cirques de Navacelles (South of France), we investigate this issue using coupled hydromechanical simulations in the framework of fully saturated orthotropic elastic porous media. By comparing the shear failure tendency for the heterogeneous DZ cases to the ones with homogeneous DZ, we highlight that: 1. Whatever the stress regime (extensional or compressional), the maximum injection pressure is greater in the heterogeneous cases; 2. Under extensional regime, the presence of the DZ limits the development of shear failure tendency in the center of the first DZ compartments directly adjacent to FC, whereas shear appears to rapidly develop along the whole reservoir thickness for the homogeneous case; 3. Under compressional regime, the presence of the DZ enhances the localization of shear failure along FC-DZ interface, whereas shear failure preferably develops in the injection zone in the homogeneous case.

Trung Kien Nguyen, Jeremy Rohmer, Ba Thao Vu
Influence of Compaction Factor on the mechanical behavior of the soils used for the earth dams in the North Central region, Vietnam

Almost all the earth dams constructed in the North Central region of Vietnam usually encounter problems related to the use of cohesive soils during dam construction under humid climate conditions with long and heavy rain periods. Therefore, it is very difficult to compact the soil to achieve the compaction factor of K≥0.97 required by the designer. In this paper, the authors present experimental results to determine the correlation between the compaction factor (K) with the mechanical behavior of the soils used for the earth dams in the North Central region of Vietnam. The research results are applied to select the reasonable value of compaction factor for the soils used in dam construction, which is suitable with the requirements of the design standard.

Van Toan Tran, Van Hien Tran
Enhanced oil recovery: A selection technique for the energy and recovery of Bach Ho field in Vietnam

With the increase in energy demand in years to come and the decrease in oil discoveries during the last decades, it is believed that the enhanced oil recovery (EOR) technologies will play an important role in energy balance. This paper presents a full review of EOR status and opportunities to increase the recovery factors in some typical reservoirs known as in-situ combustion, CO2 flooding, hydrocarbon flooding, water flooding… These methods were applied to the lower Miocene reservoir at the Bach Ho (White Tiger) oil field. Several parameters including produced oil characteristics, oil production rate, reservoir depth, etc. were considered. It was observed from some preliminary results that the immiscible gas injection is the most feasible and practical EOR method for the Bach Ho oil field.

Nguyen Van Hung, Nguyen Minh Quy, Hoang Long, Le Quoc Trung, Le Vu Quan
Overview of Geomechanics and its applications to petroleum industry – a case study for minimum overbalance pressure calculation

Geomechanics plays an essential role in drilling and production petroleum industry from beginning with pre-drill well planning and continuing with wellbore stability support while drilling and sand production management. This paper will cover an overview about geomechanics from its fundamental knowledge and geomechanical models to its applications in practical problems of oilfield operations such as wellbore instability, sand production. Additionally, a full review about input data and how to get them by measuring in laboratory and calibration with field measurement will be presented. The result shows that the Mohr – Coulomb criterion can be used for the wells with the borehole inclination from 0 to 60° in this study area.

Nguyen Van Hung
Numerical model of hydro–mechanical coupling DEM–PFV and application for simulation of settlement of soil saturated in embankment due to static loading

This paper presents the numerical model of hydro–mechanical coupling DEM–PFV using a combination of the discrete element method (DEM) for the solid phase and a pore–scale finite volume (PFV) of the flow problem. Numerical results at the microscopic scale on settlement of an embankment with soil saturated are presented denoting that the capable apply of the model DEM – PFV for predicting the settlement of granular material used in road embankments subjected to static loading. Comparison between the numerical result and the Terzaghi’s analytical solution of a soil consolidation problem shows the validation of the model DEM – PFV.

Anh Tuan Tong, Nguyen Hoang Phuong Luong
Abnormal pore pressure and fracture pressure prediction for Miocene reservoir rock, field X in Vietnam

In order to drill a well safely and economically, it is necessary to know the pore pressure and fracture pressure so that the mud density can be optimized to provide sufficient overbalance. In areas where exploration and production histories are established, offset data sets can be used to provide detailed profiles of expected pressure for those wells about to be drilled. Seismic data, log information and direct pressure measurements, production testing can be used. This article focuses on abnormal pore pressure and fracture pressure prediction by using modern methods and industry accepted concepts. Relationships between petroleum geology and drilling engineering are interpreted to give the accurate estimations of Miocene rock reservoir, field X in Vietnam. The results show that there is an abnormal pressure zone appearing from the depth of 4900ft that selecting a favorable mud density is a good solution to ensure the success and safety of the well drilling process.

Nguyen Van Hung
Study the influence of adherence edge to steel strip and soil interaction in Mechanically Stabilized Earth Wall with a self-made strip

Nowadays, high embankments are popular in many transportation networks. A method of Mechanically Stabilized Earth Wall (MSE wall) has been used for increasing the stability of backfilling soil in road embankments soil because of its economic, technical and landscape advantages. This paper presents a series of experiments on different categories of adherence edge to demonstrate the effective of edge on strain, stress-strain, and displacement of MSE wall. A FLAC software also was used to verify the experimental results. The study could provide the instructions for the design, construction and project management of MSE wall. It can also be used for suggestion of soil improvement solutions, backfilling material selections to increasing the stability of MSE wall.

Truong-Linh Chau, Thu-Ha Nguyen
Formation of Rust Scales on Mild Steel Pile in Brackish Water of Phu My Port - Vietnam

Corrosion test of mild steel (graded JIS-STK400) was investigated in brackish water environment of Phu My industrial port (Ba Ria - Vung Tau Province, Vietnam). Steel sample was exposed in 3 years. X-ray diffraction (XRD) results show that formed rust powder was composed of a-FeOOH, Fe3O4 and a- Fe2O3 in which the amount of first component is larger than second and third one. It demonstrates that natural corrosion products evolved from low to high oxida-tion state of iron by presence of dissolved oxygen in brackish environment. The mechanism of phase conversion is revealed by metallographic of rust layer cross section. a-Fe2O3 (white phase) was gathered at bank of cracking paths where was favouring diffusion of oxygen and water into inner layer. After contacting Fe3O4 (dark gray phase), corrosive agents converted it to a-FeOOH and a-Fe2O3. The phase conversion changes the weight density of materials and creates the porous tunnels in rust scales. The growth of micro tunnels to form the tunnel network allowed internal stress and cracks of rust scales evolved.

Vinh-Dat Vuong, Anh Quang Vu, Marina Kawai, Kazuhito Tsujimoto, Thang Van Le, Nguyen Danh Thao
Modelling Stress Distribution Around Boreholes

The stress distribution around boreholes plays an important role for wellbore problems. This study aims to model the stress distribution around boreholes of offshore petroleum wells. The stress model around boreholes, which is associated with the in-situ stresses, rock properties as well as the wellbore pressure and configuration, is developed. The new approach uses transformation formula of a full stress tensor including its orientations and magnitudes. A calculating program for the stress analysis of wellbores (SAoWB), which is written in Matlab language, has described and calculated all components of the stress tensor at the wellbore wall as well as around boreholes. In this study, case studies are considered using the program SAoWB based on the new approach. The field case studies are applied for boreholes of the studied wells at Cuu Long basin, offshore Vietnam. The obtaining results from our program SAoWB are in good agreement with the failure observations from high solution image logs of the studied wellbore as well as coring data. They are the bases to study its implications which benefit for offshore petroleum industry activities such as wellbore stability, optimum drilling wellbore trajectories for well planning, drilling mud selection, sanding prediction and control, hydraulic fracturing, etc. Modelling the stress distribution around boreholes from the program SAoWB not only enhances knowledge of in-situ stress tensors but also impacts on well problems, especially for offshore petroleum wells.

Khanh Do Quang, Thanh Nguyen Thi Tam, Phuc Kieu, Nhan Vo Huynh, Quang Hoang Trong
A mathematical model for fault activation by water injection

Faults in the host rock that might exist in the vicinity of deep geological repositories for radioactive waste, constitute potential enhanced pathways for radionuclide migration. Several processes might trigger pore pressure increases in the faults leading to fault slip and induced seismicity, and increase the faults’ permeability. In this research, we developed a mathematical model to simulate fault activation during an experiment of controlled water injection in a fault at the Mont-Terri Underground Research Laboratory in Switzerland.

Thanh Son Nguyen, Jonny Rutqvist, Bastian Graupner, Yves Gugliemi
A model for soil-structure interaction - Application to small modular reactors

Canada and other countries are contemplating the construction of small modular reactors (SMR) for the generation of electricity. SMRs would be built at a smaller scale than traditional nuclear reactors with anticipated lower up-front capital costs and enhanced safety features. The SMRs would need to be seismically qualified, and shown to withstand the design basis earthquake without loss of containment. In order to assess the seismic qualification of SMRs, a dynamic coupled elastoplastic-hydraulic model for soil behaviors under seismic loadings is developed. The governing equations of the model are based on conservation of momentum for the porous skeleton, and conservation of water mass. Pore water flow is assumed to follow Darcy’s law while the solid skeleton is assumed to be elasto-plastic, with the adoption of the modified Cam-Clay model to simulate its stress-strain behavior. The model is tested with the simulation of dynamic triaxial tests and a shaking table experiment. The results show that the model can capture (1) the development of permanent deformation in soil, (2) the shear-induced volume change (including both contraction and expansion), (3) the generation and dissipation of excess pore water under the dynamic loading, and (4) the strain hardening and softening behavior of soil under complex stress paths. Finally, the model is used for the scoping analysis of the seismic response of a hypothetical SMRs embedded in sandy soils.

L. Cui, M. Fall, N. Orbovic, T. S. Nguyen
Full-scale Pullout Testing of Ground Anchors to Evaluate the Applicability of French Design Practice TA95 for Vietnam

Ground anchors have been playing an important role in reinforcing dykes, underground, stabilizing structures of earth retaining walls, subway stations, and anchoring abutments of bridge or in sea port, etc. In Vietnam, the design of ground anchors is generally based on the international design guidelines, in particular the Eurocode. As there is a diversity of current design practices in different countries, it is necessary to carefully verify and validate an international design of ground anchor before adopting it to Vietnam. This paper aims at presenting a series of full-scale pullout tests of ground anchors recently performed in several projects in Hanoi and Ha Long city, Vietnam. The testing results in terms of the ultimate load-holding capacity, the pullout performance and the skin friction are discussed and compared with the French design practice TA95 in order to evaluate as well as to improve its applicability in Vietnam.

Nguyen Ngoc Thanh, Nguyen Phuong Duy
Durability Evaluation of a Geothermal Grout

The durability of a geothermal grout used to seal vertical geothermal probe is evaluated. The study integrates an experimental approach and geochemical models simulations. The accelerated ageing of the geothermal grout is evaluated in laboratory subjecting the grout to realistic geochemical and thermal aggressions to which the grout can be subjected. The parameters related to the thermal conductivity and the permeability are particularly monitored. An experimental setting is developed to reproduce the operating conditions of a geothermic probe under realistic containment conditions. The experimental results are the input of the geochemical degradation models leading to the simulation of long time scale degradation around the probe. Conclusions relating to the service life rise from this study.

Monnot Pascal, Poinclou Christophe, Blanc Philippe, Rojo Amandine, Molez Laurent, Lanos Christophe
Assessment on the performance of EPB-TBM in the construction of pilot metro line in Ho Chi Minh city (Vietnam)

Line 1 (Ben-Thanh – Suoi-Tien) of the Ho Chi Minh city Urban Railway Project is the pilot metro in Vietnam, also the first transport tunnel constructed by the earth pressure balanced single shield tunnel boring machine (EPB-TBM), of which the outer diameter is 6.79 m. Two parallel 781-m-tunnels (West Bound and East Bound) have been constructed from May 2017. They mainly locate in loose sand layers with small SPT values and the small overburden heights: 8.7 to 9 m of the former and 8.7 to 22.3 m of the latter. EPB-TBM have proven the suitability for the metro line in such geological conditions and the narrow construction site in urban areas of Ho Chi Minh city. In this paper, for the assessment of EPB-TBM during the tunnel construction, some main operation parameters of the machine in each performance routine have been analysed and the influence of the geological conditions along the alignment to the machine journey was initially studied. The study’s goal is the better understanding of the EPB-TBM performance in the first TBM metro line in Vietnam, as an experience learning for the next ones which have been scheduled to be soon appeared in Ho Chi Minh city and Hanoi.

Thu-Hang Tran, Manh-Tuan Hoang
Reusability of muds dredged from lakes in Hanoi City from its geotechnical engineering characteristics

This study is aimed at discussing on the typical geotechnical engineering characteristics of sludge dredged from lakes in Hanoi city, which have strong demand to be dredged for environmental urban. Based on which, the possibility of recyclability as filling material will be discussed. Sludge samples were collected from “West Lake” and “Hoan Kiem Lake”. A series of laboratory tests for analyzing the typically physical and chemical characteristics has been conducted. The X-ray diffraction tests (ASTM C114) and plasma spectrum analyzer tests (TCNB-ICP 01/04) were also carried out to investigate the chemical components of the muds. The test results show that the chemical components meet the National technical regulation on hazardous waste threshold and they can be disposed as normal fill. Overview on the experiences of cement treated soil in Japan reveals that the muds dredging from lakes in Hanoi City have high possibility for recycling as filling material.

Pham Tri Thuc, Phan Huy Dong
Numerical study of pile reinforced slope-A case at Khe Cham coal preparation construction site project (Vietnam)

Within the framework of Khe Cham coal preparation construction site project, evaluation of slope stability and solution of slope reinforcement are essential. A site investigation was performed first along a slope located in Khe Cham coal preparation construction site. The slope reinforcement was recommended due to a group of joints and cracks observed along slope surface. The main purpose of this study is to confirm the stability condition of the unreinforced slope and optimize the pile reinforcement (i.e., pile position, pile spacing). A numerical modeling software, Flac program, was used for this investigation. Soil properties using in the simulation model were obtained by the site investigation. Groundwater table, which was assumed to be in the top of the slope, was also considered in the model. The safety factor based-optimization analysis was performed with respect to pile position and pile spacing. Shear strength reduction method was established to determine the safety factor of the slope. As a result, the same conclusion as site investigation was found for the unreinforced slope, that is, the slope should be reinforced for the long-term stability. In addition, the sensitivity of the slope safety factor on pile position and pile spacing was discovered. Eventually, the optimization of pile reinforced slope was chosen and proposed based on the sensitivity of safety factor.

Nguyen Van Dung, Nguyen Phi Hung, Tan Do
Experimental Correlations for the Swelling Pressure of Expansive Clays in the City of Tebessa, Algeria

This paper aims to describe the dependency of the swelling pressure (Ps) of Tebessa clay soils to the conventional soil properties namely; Plasticity index (PI), dry density (γd), initial moisture content (W) and carbonate content (Ca). A statistical model, capable of obtaining an indirect estimation of Ps based on these soil parameters, is provided. High correlation coefficient (R2) of 0.93 demonstrated predictability of swelling, using multiple regression modeling. Although the above-mentioned parameters play important roles in the swelling behavior of the clayey soils, there is not any universally accepted, simple and quantitative method to classify swelling pressure at present. The equation, proposed in this paper, helps the engineers with evaluating soil pressure in practice. In addition, it can be popularized when environment conditions are satisfied for application in field explorations and design of structures over expansive soils.

Adel Djellali, Behrooz Saghafi, Mohamed Salah Laouar
Design of Experiments (DOE) techniques to Predict Swelling Pressure of Expansive Soils In Tebessa (Algeria)

This research work aims to study the swelling behavior of clayey soils in Tebessa area (Algeria) using the Design of experiments (DOE) method, based on mechanical, physical and clay mineralogy test results. The effect of different parameters such as dry unit weight, degree of saturation, water content, plasticity index, etc. on the swelling behavior of soil is evaluated and the statistical contribution of each variable in the calculated swelling pressure is also discussed. Besides, relationships between factors affecting the expansion process have been determined. The swelling pressure generated within the soil, which is useful in the design of foundations and civil engineering structures is taken as output process in the screening design methodology. Optimization of the parameters that affect the swelling behavior by Response Surface Method (RSM) allows finding the best set of factor levels to establish the mathematical model. Hence, the efficiency of this model is assessed by comparison of its output results with those obtained from laboratory tests. All of these techniques allow choosing the appropriate model that can be used for all soil conditions.

Yacine Berrah, Abderrahmane Boumezbeur, Nouar Charef, Serhane Brahmi
Analysis of Landslides In the Region of Souk Ahras (Zaarouria Sector) North- east of Algeria Using pseudo-static method

The increasing development in the region of Souk Ahras (Algeria) is more and more threatened by several landslides, i.e. mass movements of materials. Sustainability of structures and in particular roads are threatened by this widespread phenomenon in the region. Landslides cause significant damage and casualties to people and property. Practical observations of the lands in movement can establish a correlation between geological, hydrogeological conditions and the landslide phenomenon. In this study, the main objective is to combine geology with soil mechanics in order to study causes of landslides in three important sectors (Mechroha, Zaarouria, Hammam Tassa) all over the wilaya of Souk Ahras territory. In addition, we study particular landslide in sector of (Zaarouria) by modeling the mechanical behavior of the field using numerical calculations and discuss the influence of pore water pressure variation on the safety factor. Finally, the resulting model will experience the use of pseudo- static method to perceive the influence of seismicity on safety factor.

Nouar Charef, Yacine Berrah, Abderrahmane Boumezbeur
Solving the stability problem of vertical slope according to the effective stress field

Soil mechanical behavior does not agree with the elastic theory, but complies with Mohr-Coulomb yield criterion and Terzaghi’s effective stress principle. The deformation of soil as well as its shear strength depends on the effective stress. In this paper, a new direct method has been developed to determine the effective stress field in soil based on the shear potential. The method allows solving the stability problem of vertical slope.

Do Thang
Finite Element Simulation of Water Content-Influenced Progressive Failure of Sensitive Clays

Large-scaled landslides often occur in sensitive clay deposits in horsts and grabens, typical of spreads. Most large deformation numerical analysis based on the strain-softening behavior of undrained shear strength. In practice, water infiltration into soils may result a variation of non-uniform crack and shear band emergence at a low soil resistance. In this study, the mechanism of water content effect on the stress-strain relationship was implemented in Mohr-Coulomb (M-C) model using the user material subroutine of the commercial software Abaqus/Explicit. The coupled Eulerian-Lagrangian method (CEL) was used to model such large deformation analysis. The developed model was verified by a simulation of Saint-Jude landslide, which occurred in 2010 in Quebec, Canada. There was a good agreement among numerical results with water content effect comparing to an analytical function. A larger mobile soil mass movement with a significant reduction of soil resistance was simulated successfully using the developed model.

Nhat-Phi Doan, Seung-Wook Woo, Yao-Long Hou, Sung-Sik Park
Non-microbial carbonate precipitation as an improvement technique of sand

In this study, the formation of artificial Calcium Carbonate (CaCO3) from the reaction between Calcium Hydroxide (CH) and Carbon Dioxide (CO2) was taken into account to improve sand properties. Firstly, Jumunjin sand was mixed with 2% of CH and water at a constant water-solid weight ratio of 0.1 before curing in a carbon dioxide chamber. The precipitated calcite content was investigated by the variation of CO2 chamber pressure and number of repeatable treatment. Then, unconfined compression tests of such samples were carried out to evaluate the influence of calcite content on mechanical properties of sand. It indicated that as increasing of repeatable treatment, the UCS of treated sand increased due to the higher of calcite precipitation. The first and fifth cycle do not lead to any significant variations of precipitated calcium carbonate content (CCC) and unconfined compressive strength (UCS) with the change of carbon dioxide chamber pressure from 100 kPa to 200 kPa, but- the higher CCC and UCS can be seen clearly at the tenth cycle. After 10 treated cycles, the UCS of CP1.10 and CP2.10 were 5 times greater than CP1.1 and CP2.1, respectively. The maximum UCS was 361 kPa of CP2.10 specimen. The stress-strain curves obtained from UCS test at 200 kPa CO2 gas pressure exhibited more strain at peak stress than that at 100 kPa and the samples subjected to 10 treated cycles has more ductile behavior than other samples.

Sung-Sik Park, Trung-Tri Le, Seong-Heon Kim, Zhenzhen Nong
Modeling on Cuttings Transport in Inclined and Horizontal Well Drilling

In inclined and horizontal well drilling, cuttings transport is playing a very important role in obtaining a safe and efficient drilling plan. The paper presents two empirical models, namely Larsen’s model and Rubiandini’s model, which were considered to evaluate the cuttings transport in both inclined and horizontal well drilling in offshore Vietnam. A parametric study considering different drilling parameters such as mud weight, rate of penetration (ROP), mud rheology, etc. indicated that the two empirical models provided the same trends of the flow velocity and flow rate required for transportation of mud cuttings. It is concluded from all simulations that the flow rates predicted by both Larsen’s model and Rubiandini’s model are reasonably close to the actual flow rates in the drilling operation. Moreover, it is also observed from the analyses of the horizontal drilling case that the use of Rubiandini’s model could generally result in larger flow rate required for cuttings transport compared to Larsen’s model.

Do Quang Khanh, Truong Trong Tuan Dat, Kieu Phuc, Tran Thi Mai Huong, Hoang Trong Quang
Study on Cement-Treated Soil with RoadCem Additive in Construction of Rural Roads: A Case Study in Viet Nam

The use of soil in place for road construction could reduce construction cost and environmental impact because this method can replace the traditional materials that are depletion such as sand, gravel. This paper presents the laboratory results for selecting proportion and inspection testing results of experimental road construction using cement-treated soils with RoadCem additives. RoadCem additive improved the hydration of cement when cement reacts with soil particles, thus increasing the strength of reinforced soils, especially tensile strength. The results of inspection tests showed that the average of compressive strength, tensile strength, and modulus elastic in the saturated condition of reinforced soil satisfied the design and standard requirements in Vietnamese standard.

Ba Thao Vu, Thi Thanh Huong Ngo, Quoc Dung Nguyen, Anh Quan Ngo, Lanh Si Ho
Application of Steel Pipe Piles with Wings installed in Soil Cement Column for Building Structure in Vietnam

The steel pipe piles with wings installed in soil cement (referred to as ATT) developed in Japan and Vietnam are composite foundation piles made of steel pipes with wings with foundation improvement pillars (referred to as columns) in soil cement and spiral wings attached to the shaft intermittently. This kind of composite foundation pile has large vertical and horizontal bearing capacities and is a construction method of foundation piles with consideration of environments with little surplus soil, using steel pipes with small diameters. In this study, after introducing ATT’s overview and construction process, application of this composite foundation piles for a building structure was introduced. The in situ loading test results was also presented. Furthermore, from results of loading tests done in the application project, the loading capacity and consideration of ATT’s applicability in Vietnam was verified.

Pham Hoang Kien, Daisuke Ito
Modelling the hydromechanical behaviour of a granular expansive clayey soil upon hydration using discrete element method

Bentonite-based pellet materials are considered as a sealing material for the isolation of galleries in the French radioactive waste disposal concept, owing to operational convenience. The influence of the granular nature of the material is studied through Discrete Element Method (DEM) simulations. Each pellet is modelled individually and represented by a sphere of same mass and density as real pellets. Swelling pressure tests of pellet mixtures, carried out at laboratory scale, are simulated using a model describing the hydromechanical behaviour of a single pellet upon suction decrease. The mixture behaviour is satisfactorily reproduced upon hydration from 89 MPa (initial state) to 7 MPa of suction. The model is then used to study the behaviour of large granular assemblies of bentonite pellets on the same hydration path. Results highlight that the mixture assembling process, the pellet strength and stiffness, and the mixture density have an influence on the swelling pressure development upon hydration. Numerical results obtained through DEM simulations will be of interest for future Finite Element Method simulations of the full hydration path using double structure models where pellets correspond to the microstructural level.

Benjamin Darde, Jean-Noël Roux, Patrick Dangla, Jean-Michel Pereira, Anh Minh Tang, Jean Talandier, Minh Ngoc Vu
Spatially-varying non-stationary seismic bedrock motions

Seismic bedrock motions required for full soil-structure seismic analysis have not always been available and are simulated in this paper. The stochastic bedrock Fourier spectrum used accounts for source spectrum, attenuation, geometrical spreading and source-to-bedrock amplification effects. Earthquake magnitude, geometrical properties of the source and the bed, and geological profile including the source and path rock are the input. The simulation is further enhanced by authors’ new developments as follows. The frequency-dependent source-to-bedrock amplification factor evaluated by a numerical scheme improves the bedrock Fourier amplitude spectrum. The parametric modulating functions obtained for a specific earthquake magnitude and source properties facilitate the spatiality and non-stationarity. The parametric forms of lagged coherency compatible to specific bedrock sites also ensure the spatiality content. The case study consists of three consecutive examples of the same geometry, where the variation of source-to-bedrock amplification factors at several bedrock depths is investigated. The formulated bedrock Fourier spectrum is then validated. The spatially-varying non-stationary site-compatible bedrock motions are finally simulated where the differences between the averaged Fourier spectra of a realization of 100 simulated accelerograms at two bedrock sites are observed.

Van Nguyen Dinh, Biswajit Basu
An experimental investigation on bearing capacity behavior of rectangular footing over reinforced soil slope

Various Geotechnical engineering works demand the construction of foundation over cohesive soil slope. The construction of foundation over these soils may cause higher settlement which can obliterate the overlying structure. On the other hand, the use of reinforcement techniques in the soil stability is also increasing rapidly. Amongst them, the use of geosynthetics to reinforce the foundation soil is one of the cost-effective options. In the present study, a number of model footing tests were performed in laboratory to check the effect of geosynthetics in the development of bearing capacity on shallow foundation resting over cohesive soil slope. For this purpose, a bi-oriented geo-grid was chosen as a reinforcement material. Parametric studies such as effective depth of reinforcement, number of reinforcement layers, were considered in the present study. A number of laboratory tests were conducted, and their results were analyzed. From the analysis it was observed that soil reinforced with geosynthetics overlain by rectangular footing showed substantial increase in ultimate bearing capacity of the reinforced soil, thus signifying the potential benefits of reinforcements in soil.

Raju Sarkar, Amit Kumar Shrivastava, Ankur Mudgal
Meshfree SPH modelling of shrinkage induced cracking in clayey soils

In this study, a computational approach that combines the mesh-free Smoothed Particle Hydrodynamics (SPH) and a simple anisotropic damage constitutive model is proposed to model shrinkage induced cracking in clayey soils. To assess its performance, a numerical soil shrinkage test is conducted and simulation results are compared with experimental data. Numerical results show that the proposed approach can capture complicated cracking patterns with multiple fracture networks in clayey soils, which demonstrates the potential of SPH for simulating desiccation cracking in these materials.

Hieu T. Tran, Nhu H. T. Nguyen, Giang D. Nguyen, Ha H. Bui
Numerical predictions of post-flow behaviour of granular materials using an improved SPH model

This paper presents the recent development of the smoothed particle hydrodynamics (SPH) method for accurate predictions of granular flows. Granular materials are described within the classical plasticity theory framework, while the large deformation and flow behaviour of the materials are simulated by the mesh-free SPH. To improve the accuracy of SPH for the post-flow prediction at which stress fluctuation under large shear deformation is usually observed, a stress regularisation technique recently proposed by the authors is adopted. Through several numerical validations with experiments under 2D and 3D conditions, the proposed SPH model shows significant improvements in the accuracy and stability of SPH not only for simulations of granular flows, but also for general applications for solid materials.

H. H. Bui, Giang D. Nguyen
Stochastic Site Response Analysis in Consideration with Various Probability Distributions of Geotechnical Properties

Site response and soil profiles are a function of one another, and the probable distribution of soil profiles have significant effects on the site response. This study presents the effects of random variations of geotechnical properties on the site response using the different probabilistic distributions. The uncertainties of soil properties including shear wave velocity (), the density, and the nonlin-ear soil properties are investigated and applied for the site-specific in the United States. A computer program, PSHAKE, written in Python has been developed for solving the variabilities soil properties via Monte Carlo Simulations. The com-patibility and the enhancement of the proposed procedure are verified with the variability in using the Toro model. The outcomes obtained from PSHAKE are verified based on the agreement with the reference solution given by the program Strata. Additionally, the results in sensitivity analysis indicate that uncertain unit weight has a smaller impact than the material degradation curve on probabilistic model.

Thanh-Tuan Tran, Phu-Cuong Nguyen, Seung-Ryong Han, Dookie Kim
Analysis of strain measurements in large span soil-steel bridge structure

In this paper the effects of live loads on the displacement of the corrugated steel structure buried in soil, i.e. soil-steel structure, will be analysed. The loads are movable, but have characteristic of static passes. The results of strain measurements with relatively dense layout located around the periphery of the corrugated steel structure are used to calculate its deformations.By using dense layout of strain gauges any direction of the structure displacement can be calculated based on the changes of the strains in the analysed circumferential strip (part) of the structure. Simple FE models are constructed in order to accurately perform such calculation. Note that the existing analytical calculations method dedicated to soil-steel structures do not provide any possibility to calculate deformation of the steel shell. Therefore, this paper describes sufficient methodology that allows to calculate steel shell deformation in soilsteel structures bridge subjected to different live load models.

Czesław Machelski, Adam Czerepak, Piotr Tomala

Urban Planning, Transport and Environment

A Landscape Structure Proposal for a Sustainable Development – Quy Nhon City

According to Asia 2050 (ADB 2011) the Southeast Asia’s urbanization rate will increase from 42% in 2010 to 65% in 2050. In the face of this, the Viet Nam government approved its National Green Growth Strategy (2012) which complements the Framework Master Plan for Urban Development in Viet Nam to 2025 and the 2050 Vision. This framework comprises a balanced and strategic growth through the development of secondary and tertiary cities, as Quy Nhon City (QNC), as hubs within provincial urban systems. The Green Cities Action Plan embodies ADB’s new Green Cities approach urban development by means of the 3E lens (environment, economy, and equity) aiming to develop cities in a sustainable way to be green, competitive, and inclusive in an environmental, economic and social way. Within the Green Cities framework, we propose a new design approach to QNC planning. This approach based on landscape systems is materialized in a continuous and productive landscape structure promoting the occurrence of ecologic, economic and social processes. This multifunctional structure is fundamental for the sustainable growth of cities such as QNC, enabling a realtime response to ecologic current fragilities faced by urban spaces, preservation of cultural values, heritage, and identity, aesthetic concerns and leisure. It also enables partnerships among the local and central government, the communities and the private sector, industry and enterprises. These partnerships will address the problems, identify and implement the adequate solutions to these issues without compromising social equity.

Rute Sousa Matos, Huyen Thi Nguyen, Tho Van Phan, Phan Thi Le Thuy
Travel behavior change patterns under adverse weather conditions - A case study from Ho Chi Minh City (HCMC), Vietnam

In major cities, road flooding caused by heavy rain and/or high tidal rise frequently happen and cause road traffic congestions and accidents. To help design effective traffic management measures for HCMC, this paper focuses on a survey of the people’s travel behavior changes under the adverse weather conditions. A revealed adaptation interview survey was conducted on 400 road users in 2018. Typical patterns of travel behavior changes and influential factors were analyzed based on the surveyed data and by using the Pearson Chi-square Independence Test. While trip cancelation, delayed departure, waiting for resuming of trip, route change, and destination change are significant, mode change is very modest. A road flood causes the changes more strongly than a heavy rain. Influential factors to such changes are trip characteristics, including trip purpose, trip length and frequency, and personal characteristics. The results would be input data for travel demand forecasting model in adverse weather conditions, and then helpful in formulating traffic management strategies to mitigate the negative traffic impacts of urban floods and heavy rains.

Anh Tuan Vu, Thi Thanh Huong Nguyen
Traffic Impact Assessment of Infrastructure Development Projects for Sustainable Urban Growth

Infrastructure development projects in urban areas often create im-pacts on the urban life. As the size of the projects increases, undesirable effects such as traffic congestion, traffic accidents, and environmental problems may become unacceptable to the community. In Vietnam, there witnesses rapid de-velopment of infrastructures, especially high-rise buildings in the big cities. These infrastructures generate high traffic demand and may cause serious traffic congestion on the surrounding transport network, thus assessment of traffic im-pacts (TIA) imposed by the projects is essential in controlling spontaneous de-velopment for sustainable urban growth. For TIA to be actuated, there should be a statutory document that institutionalizes the requirements on conducting TIA in the project appraisal, and a technical framework that guides the struc-ture, content, procedure and method for TIA execution. However, in Vietnam, such essential documents are not yet available. This paper reviews TIA imple-mentation in some countries, addresses issues in TIA execution practice, figures out the key contents of a TIA report, and proposes solutions to actualize the execution of TIA for development projects for sustainable urban development in Vietnam.

Trinh Dinh Toan, Dao Van Dong
Reasons for cyclists denying new-built bicycle lanes

Recently, cycling has been considered as one of the most potential sustainable transport modes in cities. Therefore, a great deal of bicycle facilities has been built in them. One of the most popular facilities could be the bicycle lanes (BL). However, in some cases, cyclists tend to deny using the new-built BLs. This can be viewed as a significant waste of resources. The present study aims to indicate some factors that prevent cyclists from using the BLs. To do so, initially, the effects of the impacts factors on the facility choice of the cyclists were investigated, based on an objective camera-observation survey in the daily cycling environment. Then, the impact trends were validated and explained based on an independent subjective stated preference survey. The results showed that perceived safety was the most important aspect that decides whether they choose the BL or not. Several factors, including high vehicle volume, the existence of real-time stopping vehicles on the BL, gender, narrower width of traffic lanes, narrower width of BL, and wider sidewalk were found that negatively affected the probability of the cyclists on their choice to ride the BLs. These findings can help developers, planners, and designers to adopt more reasonable investment decisions as well as better designs while developing bicycle facilities.

Nguyen Duc-Nghiem, Nguyen Viet-Phuong, Hisashi Kubota
Sustainable and Health-Oriented Transport Planning and Urban Planning

The proportion of people living in cities is increasing in developed as well as developing countries. Besides the positive effects of urbanisation there are also negative impacts on human health, for example due to heat islands, air pollution and noise. Health is of high importance for the citizens, and in our societies the awareness for health impacts is increasing due to more welfare. However urban planning as well as transport planning are not considering health impacts sufficiently, so far. Consequently, a sustainable, health-oriented and integrated urban and transport planning approach is urgently needed to provide a high quality of life in a healthy urban environment. Upcoming changes in vehicle technology and transport services will induce and require new urban forms. The growing individual interest in improving the personal health situation will furthermore contribute to the high demand for an integrated approach. In order to derive adequate processes and measures in the field of urban and transport planning to improve human health and environmental conditions, the interdependencies between urban form, transport system and health are elaborated.

Karin Menges, Manfred Boltze
Integrated Transport Planning for Sustainable Urban Development – Singapore’ Approach and Lessons for Vietnam

This paper examines Singapore’ approach to integrated transport planning for sustainable urban development, and draws lessons that may be applicable for large cities in Vietnam. The paper explores strategic planning approaches Singapore applies for transport and land use integration, and the planning instruments Singapore deploys to integrate different transport modes physically and institutionally. It learns the way Singapore plans a city to make the city liable and sustainable, and proposes relevant points under the subject of integrated transport planning for Hanoi and HoChiMinh cities in Vietnam.

Trinh Dinh Toan, Dao Van Dong
Transitioning Different Stages of Transport Planning in Urban Areas: Experiences of Singapore and Vietnam

Level of urbanisation – as population density and transport demand – is rapidly increasing in many cities. Planning approaches vary from city to city and authorities everywhere are being challenged to provide sustainable infrastructure that meets social needs, maximise space and benefits. Transport planning, especially in urban areas, is crucial as it influences sustainable city-growth and space-usage. Transport planning can be classified into three stages, which evolve with level of urbanisation and other city’s characteristics: (1st) vehicle-based, (2nd) person or trip-based, and (3rd) liveable-city.This study presents an overview of the three transport planning stages and relevant examples. For each stage, the study discusses factors such as capacity, social needs, different modes of transport, features of the built-environment, emerging technologies (where applicable), and sustainability impacts. The focus is on planning approaches from Singapore to enhance the long-term vision for sustainable urban development of big cities in Vietnam. Singapore, being currently in the 3rd stage of planning, is focusing efforts in providing inclusive infrastructure and promoting sustainable modes of transport. Ho-Chi-Minh City and Hanoi are still focused on motorised transport with low rates of walking and cycling. Lessons from Singapore to Vietnam are delineated accordingly.

M. C. Rojas Lopez, T. D. Toan, Y. D. Wong
Analysis of Mode Choice Behavior under Adverse Weather Conditions Using RA and SA Surveys - A Case Study from Ho Chi Minh City (HCMC), Vietnam

This paper analyzes mode choice behavior in different weather conditions, with population groups, on travel purposes and travel distances to support the formulation of weather responsive traffic management measures. Revealed and stated adaptation surveys are carried out with 400 respondents and 100 respondents, respectively. The survey shows that the rate of mode change due to adverse weathers is much smaller than the figure in developed countries. The major patterns of mode change are shifts from motorcycle to car or taxi, accounted nearly half of mode changes, thus causing severer traffic congestions. The mode choice modelling show travel time, travel cost, gender, income, specific jobs, motorcycle ownership, bus ticket holding, provision of weather information prior to the trip are significant factors to mode choice decision under bad weather conditions. The results suggest focusing on “avoid or reduce unnecessary mobility demand” and “improve public transport” measures.

Vu Anh Tuan, Nguyen Thi Thanh Huong
A Study on Motorcycles Overturning due to Strong Wind and its Warning System

Motorcycle is a typical transportation mean in Vietnam. In present, motorcycles travel in strong wind conditions is always difficult and can lead to unacceptable accidents that may have an adverse effect for people who ride the motorbike. In this case, so many accidents are in relation to motorcycle because of strong wind when the resident move on the bridges. In general, there are various researches about car overturning in development country but the overturning of motorbikes is quite new and not so much researches mentioned about this. In current study, the authors give an overview of the effects of motorcycles when subjected to win. Furthermore, authors try to build the risk curves, analyze the data and provide a regulation system for motorcycle in strong wind conditions. The warning work is based on wind speed and wind direction. Then, based on the relationship of the wind speed and wind direction with motorbikes velocity, the system will send the warning messages for motor-riders. Especially, the renewable power also uses to operate the warning system which can make it become more efficiency and sustainable.

Vo Duy Hung, Do Anh Vu
Bus signal priority by active signal program – A case study in Ho Chi Minh City (HCMC), Vietnam

The bus signal priority (BSP) has been applied in many cities world-wide. However, it has not been implemented in Vietnam, particularly in Hanoi and HCMC where traffic congestion happens every day due to i) the limitation of space for expand road infrastructure; ii) the limited level of technology integration in Vietnam; iii) the budget constraint; iv) the poor traffic management system; v) the traffic participants’ awareness; and so forth. Although the BSP has been suggested by many experts, no feasible solution of BSP for HCMC has been proposed. Therefore, this research shall focus on the application of ASP (active signal controller program) aiming to prioritize buses in mixed traffic flow in HCMC. The traffic management theory is combined with, the smart signaling system technology (automatic vehicle location (AVL) and advanced signal control systems) in this research. The BSP is expected to improve the bus quality service, which will encourage people to use bus in daily activity instead of motorbike. Besides, the economic loss and the air pollution caused by time delay and petrol consumption is also expected to reduce.

Thi Thanh Huong Nguyen
Modeling land use change based on Remote Sensing, GIS and Algorithm Cellular Automata decision support sys-tem for urban sustainability planning in Quy Nhon, Binh Dinh province central Vietnam

A study on the prediction of land use change and its spatial and temporal variability had been studied for Quy Nhon city for a period of 18 years via land change model with approaches based on remote sense images obtained from sensors Landsat and Markov string was used to model land use change. In order to predict land use changes, the study conducted on the creation of mapping land use classification from remote sensing image and to assess the accuracy of the classification result by the Kapa index. Validation will be essential to the prediction of land use changes and future urban expansion, until 2027 and 2035, contributing to the orientation of future land use planning.

Tho Van Phan, Tu Anh Ngo, Huyen Thi Nguyen, Rute Sousa Matos, Trang Thuc Dang
Modeling and applying heuristics for optimization of solid waste collection under consideration of vehicle capacity

The main contribution of this paper is to propose a general network flow optimization model for the problem of solid waste collection related to garbage management and transportation route planning. A model is formulated for a specific case in a big city in Vietnam. With the continuous increase of urban population in big cities of a developing country and the arising problem of waste management over the years, attempts have been made to organize the process of collecting solid waste from households and a series of tasks to ensure the best logistical steps. Considering the network of depots and information about the vehicles, we propose to apply heuristic algorithms from Operations Research to optimize the routes for vehicles to travel to depots and back. The research question thus concentrates on sequencing and routing with similar solution concepts as a classical Traveling Salesman Problem. For generating solution and implementation, we apply Evolutionary Algorithm using a commercial Solver tool. In general, network problem include cost of moving materials through a network involving varying demands, parameters, and constraints depending on the locations that the materials are being brought to. Problems of these type are characterized network flow optimization. The consideration of the connections between different parts of the network with inputs and outputs is what makes these problems difficult, but on the other side quite practical and applicable. The visual effect of a network flow model makes it useful for planning activities on the management level. Using numerical examples, we show that the efficiency of the evolutionary algorithm in the defined problem instances is better than any greedy approach. Finally, we discuss the similarity between the proposed model for solid waste collection and the problem of routing order pickers in multiple block warehouses.

Hai Dung Dinh
Effective Capital Usage Solutions for Road Infrastructure Maintenance in Vietnam

In recent years, the road infrastructure system in Vietnam has developed rapidly, sustainably, in a modern direction with key points. The competitiveness index for the road quality in the period of 2015-2016 is ranked 93rd, an increase of 11 levels compared to the period of 2014-2015. Achieving such results, besides increasing construction investment both in width and depth, the role of road maintenance is indispensable. After 2013, when the Road Maintenance Fund is put into operation, the tolls on motorized vehicles are collected and the capital allocated for the national highway maintenance in the period of 2013-2016 is 6392,24 billion VND/year on average, it is greatly increase comparing with the previous period. However, the capital usage management is still inadequate. By analyzing the policies, status of management for road maintenance capital usage in Vietnam; using the results of running SPSS software for investigation and survey, two groups of solutions have been pointed to improve the management of the capital usage for road maintenance. Two groups are: completion the allocation mechanism for local road maintenance fund and legal system related to capital usage management to ensure the efficiency and sustainability of road traffic infrastructure.

Nguyen Thi Tuyet Dung, Nguyen Quynh Sang
Perspectives of the use of GPS in travel survey: Research on identification of missing trips in a GPS pilot survey in Hanoi

GPS-based data collection methods have become particularly popular in travel behavior research, mainly because of the worldwide coverage and the accuracy of the GPS system. This paper identifies the missing trip data obtained by two methods survey reported and GPS recorded in the same days. This study shows that the GPS survey can be used successfully to complete the conventional transport surveys, but it is still too early to predict the complete substitution of conventional survey by the GPS mobility survey.

Thanh Tu Nguyen
Satelite image application for assessing the effect of urbanisation to temperature at Danang City, Viet Nam

The infrastructure development for economy is really imperative towards developing countries. Therefore, this process brings several unexpected impacts. Landcover change caused temperature increase is noticeable thing. This impact along with global warming bring out significant consequences about the health, the economy and the society. For the purpose of analysis the effect of urbanisation on temperature variation, this study processes the Landsat satellite image over forty years. The result is expected to find out the relation between the urbanisation process and city warming. It might be the crucial basic for planning the urban area more effective and more sustainable, as well for mitigating the negative impact on the public health. In this paper, the authors will present several results of the temperature variation due to urbanisation over the pats forty years.

Ngoc Duong Vo, Quang Binh Nguyen
Dambreak Simulation at Thuan Ninh Reservoir, Binhdinh, Vietnam

With more than 160 reservoirs, Binhdinh is considered as the province having the most reservoirs over the country. This system have contributed importantly for provincial socio economic development. Therefore, the reservoirs in Binhdinh comprehend many potential risks due to their ages, noticeably the Thuan Ninh reservoir (Vhi= 32.26 106m3) which was constructed for 1970s. In order to help the local authority to respond actively with urgent incident, the study is to simulate dambreak incident for Thuan Ninh reservoir. The study is realizes relied on MIKE FLOOD model. The modelling scenario is supposed following the standard of TCKT 03:2015/TCTL. The simulation demonstrates that the Thuan Ninh dambreak incident might affect 33.35 km2 at downstream area. The lag time, inundated time and flood depth are also considered in the study.

Ngoc Duong Vo, Quoc Hoang Anh Huynh, Trung Dung Vo
Flood Mapping for Downstream of Ben Hai River, Vietnam

Flood map nowadays is seen as an indispensable tool in urbanism, flood prevention and mitigation. For this reason, establishing flood map is mighty necessary for developing the socio economy of a river catchment. Ben Hai is the second largest river at Quang Tri province – Viet Nam central region. Besides the positive role towards the local socio economic development, the Ben Hai river in resent years has caused lots of disasters, specially on inundation. With the aim of providing an overview for mitigating the natural disaster consequences, the study is used the MIKE FLOOD-DHI to represent the Ben Hai river flooding. The model is set up for an area up to 100 km2. The flood maps are established with five historical flood events and several assumptions. The result is expected to provide the basic scientific evident for local authority to redude the impact of natural disaster, also for sustainable development.

Ngoc Duong Vo, Truong Son Ho
A Framework for Last Planner System Implementation in Egypt

The Last Planner System (LPS) has been the focus of several studies in the Lean Construction community. Previous research has focused on defining lean in construction, its implementation in various projects, and the challenges facing the implementation. However, no research has addressed lean implementation in Egypt. Therefore, this paper addresses the obstacles facing LPS adoption in the Egyptian construction industry and proposes a framework for LPS implementation in Egypt. A questionnaire survey is carried out involving a number of construction industry stakeholders to identify the current market knowledge on LPS and the challenges expected from its implementation in Egypt. The proposed framework details the techniques to be followed during the project life cycle and how to measure the effect of LPS on the overall project performance. The framework also tackles the expected challenges and proposes key solutions for each one. This paper aims to push the boundaries of the current state of the construction industry in Egypt by proposing the implementation of LPS and the steps needed for its adoption in Egypt.

Eyad Aboseif, Rana Khallaf
Climate Change Impact on Urban Flooding in Quynhon City, Vietnam

Flooding is one of the major problems in many cities. Adequate development of a drainage system is a primary measure the city used to deal with the problem. However, the risk of exceedance of design flood is more likely to increase due to the impact of urbanization as well as climate change. Changes in rainfall pattern and sea level rise increase the risks of inundation of city dwellings and amenities. This paper investigates the changing of flooding performances using the Stormwater Management Model (SWMM) to describe the impact of climate change on drainage in Quy Nhon city, Vietnam. Climate scenarios are developed for future 2050 and 2100 by following the emissions proposed in IPCC representative concentration pathways (RCP) of greenhouse gases. The results examined the future flooding areas and their durations. It also highlights the inappropriateness in drainage design which could contribute to flooding increase in the city.

Duc Phuoc Vo, Muhammed A Bhuiyan, Ngoc Duong Vo
Health Impacts of Traffic-related Air Pollution: Cause-effect Relationships and Mitigating Measures

The health impacts of traffic-related air pollution (TRAP) are one of the major concerns regarding the sustainability of the transport sector. Particularly in urban areas, transport is a main contributor to air pollution and affects a large part of the population due to the high number of motor vehicles and urban population. Recently, the evidence from epidemiological studies on the health impacts of TRAP has increased significantly. The major evidence indicates that TRAP increases the risk of mortality and morbidity. Despite the significant improvements in reducing vehicle emissions, TRAP is still increasing in many areas worldwide and becoming a global threat to human health. In order to solve the problem, a clear understanding of the existing situation is necessary. Therefore, a comprehensive cause-effect relationship between TRAP and its health effects is developed, using the Driving Force-Pressure-State-Exposure-Effect-Action (DPSEEA) framework. Then, some measures for mitigating the health impacts of TRAP are presented.

Huong Le Thi
Evaluation of the Effects of Traffic Management at School Areas

Traffic accidents are known as one of the leading causes of mortality among teenagers and young adults in Vietnam. Specifically, the risky road behavior lead to 6.2 per cent of killed and injured persons are youth aged between 0 and 18 years. While children injured or killed when walking or travelling as passengers in motorcycles are a serious concern in Vietnam, it is obviously that road users perceive on traffic safety for children is one of the most significant factors affecting accident reduction. The proper application of traffic management measures at school areas needs to be recognized as one of the most com-mon and vital ways to improve traffic safety for children.

An Minh Ngoc, Khuat Viet Hung
Policy Implications from Traffic Accident Analysis: A Study Case from Vietnam

According to the statistics of Vietnam, the impact of traffic accidents cost accounts for 2.5% of GDP. Thus, evaluating and analyzing the damages caused by traffic accidents has become more significant during the last decades. It is necessary to find out the effective approaches to identify the influencing factors of traffic accidents. Among many regression accident-frequency models, Classification and Regression Tree Analysis (CART), one of the most popular data mining techniques and has been applied in many areas of business administration, medicine, industry, and engineering fields, etc., is invited in analyzing traffic safety problems. The results showed that when there are motorcyclists involved in accident, the probability of fatality increases up to 61%. Therefore, searching the solutions for ensuring motorcycle safety should be placed on the first priority in Vietnam.

An Minh Ngoc, Truong Thi My Thanh
Analysis of Tourist Travel Behavior and Recommendation for Active Transport Encouragement Strategies, the Case of Hue City

Over the past years, several transport encouragement strategies have been implemented to stimulate the mode shift from motorized transport to walking and cycling from international studies. However, information concerning the effectiveness of such strategies in tourism cities in Vietnam is still limited. This study aims at recommending strategies to encourage active transport usage of tourists through the analysis of travel behavior. The study firstly reviewed literature to propose travel modal shift measures that specified for local travel characteristics. Secondly, travel interview survey was conducted in Hue city to understand the current travel status of 259 tourists and the possible encouragement measures on mode shifting to walking and cycling. Finally, the study showed the core encouragement measures concerning the possibility of mode shift under tourist perspective. Combination of more than one measures revealed the most possible effectiveness and applicability to implement mode-shift strategies.

Truong Thi My Thanh, Dong Van Dao, Hai-Bang Ly
The Impacts of Urbanization on Urban Flooding in Danang City, Vietnam

Danang City has been undergoing rapid urbanization during the past decades. The changes in land use associated with urban development have an adverse impact on the urban hydrological processes, which may result in the increase of urban flood risk. In this paper, Mike 11 and Mike 21 models were used to simulate flood processes for different land-use scenarios and the possible effects of urbanization on flood characteristics were checked. The results show an increase in the risk of flooding in the area where there is a major change in urban infrastructure. The study outcomes can provide essential information for urban planning as well as propose solutions to respond to flooding in the context of rapid urbanization epoch.

Thuy Nga To, Huy Cong Vu, Hung Le
Factors Influencing the Choice of Bike Sharing System: An Investigation of Visitors and Local People in Vietnam

Bike Sharing System (BSS) has become a popular travel mode to satisfy urban residents travel in many cities in the world. This paper examines the influencing factors of BSS choice of 2 group: visitors and local people. For tourists, they are the person who has used the bicycle in the past; have travel duration from 3 to 7 days and most of them come from the US (for foreign tourists). Besides, the visitors who use the car/coach during their trip are negative for BSS. The residents who are students or individual business, have habit to use bike, undertake 3-4 trips per day with the short travel distance and have lower income, are more likely to use the BSS. The identification of these influencing factors plays an important role in the deployment of bike-sharing systems in the big cities in Vietnam. Several policy recommendations are proposed based on these results for government and BSS investor in order to have the effective BSS in Vietnam.

Thanh Tu Nguyen, Thu Huyen Le
Flood risk assessment in the planning of new urban in Quangnam province, Vietnam

During the last 10 years, Central Vietnam has observed rapid urbanization. Urban flooding is a new disaster and few studies were carried out in this area. Researching to determine the frequency of flood control for these urban areas as well as assessing the flooding impacts of surrounding areas is very urgent. This study will show the importance of determining the frequency of flood prevention of new cities. This frequency must be chosen to both ensure flood protection for the project and not to flood the surrounding areas. In this paper, urban area of Canh Dong Nhong in Quangnam province was chosen as case study.

Thuy Nga To, Hung Le, Huy Cong Vu
Low Impact Development, a novel technique for cutting down urban flooding in Quynhon city, Vietnam

Many coastal cities are becoming more vulnerable to flooding due to increases in extreme precipitation as a consequence of climate change and reduction of infiltration due to urbanization. Application of Near-natural stormwater management measures such as Low Impact Development techniques (LIDs) is considered as an alternative option to reduce the risks of urban flooding caused by climate change and urbanization. This technique reduces inundation possibility by using natural or man-made systems to filter and recharge stormwater into the groundwater. In this research, applicability of two LIDs, infiltration trend and swales, was evaluated with case study in Quynhon, Binhdinh province, Vietnam. The results show that, the LIDs work effectively to reduce peak flood and enhance recharged amount groundwater in short duration rainfall. Their effects, however, depend on reaching saturation points of applied measures.

Nguyen Duc Phuoc Vo, Muhammed A. Bhuiyan, Ngoc Duong Vo
Vehicle Usage/Ownership control for a Sustainable Transport system in the Motorcycle Dependent Cities

There is a distinguishing characteristic between traffic flow in Vietnam (and in many other Asian countries) and those in developed countries: two-wheeled vehicles (so-called motorcycles) consist a high percentage in the road traffic system. Motorcycles, for their special advantages, play a dominant role in the traffic flow in Vietnam cities, leading to the context of traffic depending on motorcycle (so-called motorcycle dependent cities- MDCs). The transportation system in MDCs is facing with a lot of chaotics and problems, such as congestion, pollution and traffic accidents. Recently, there have been a lot of traffic control measurements conducted in the effort of solving the problems. Unfortunately, there is still very little that cities know about managing this mode. This article describes work undertaken to provide a better understanding of motos and what might be done to better position their role in providing urban mobility. Lessons learned and potential solutions for Vietnam could be widely informative across East Asia and other regions where developing cities are facing similar challenges.

Le Thu Huyen, Nguyen Thanh Tu
Typhoon Wave Modelling for Viet Nam Central Region

Coastal zone plays a very important role in Vietnam socio-economic development, especially with the central region. However, the coastal line in Vietnam central region has been changed seriously. It becomes more complicated in recent years when shoreline erosion has occurred in many localtities. The consequence of this natural phenomenon has affected significantly to these area. The sea level rise and typhoon wave are considered as the main causes of unexpected phenomenon. With the aim of mitigating the impact of typhoon wave to coastal line in central Vietnam, this study is realised. By using Mike softwave family of DHI for coastal zone from Binh Dinh to Binh Thuan, Viet Nam, the result will allow not only us to understand, predict and design mitigation measures to combat the effects of these typhoons, it will also allow us to develop a methodology to be used elsewhere on the Viet Nam coast. The model is calibrated and validated versus water level data of Quy Nhon station and of two other temporary stations in central area, also compared to WAVEWATCH III model result with high performance. Result from four different typhoon scenario (from level 6 to level 12) are analysed to provide basic information about the wave situation then estimating their impact to study area.

Ngoc Duong Vo, Quang Binh Nguyen, Cong Phong Nguyen
Application of Win-TR55 for Calculating Designed Flood in Small Watersheds in Mountainous Region of Vietnam

Transportation infrastructure plays a significant role in the development of a nation. Development of this infrastructure in Vietnam is facing difficulties, especially in mountainous areas due to lack of rainfall and flow data for calculation of designed flood. Additionally, many water drainages have been damaged by heavy rain and severely affected by climate change. The program Win-TR55 based on SCS method is a technical procedure for calculating storm runoff volume, discharge, and hydrography. In order to use TR55, parameters for calculating designed flood including rainfall, soil type, and land use map are required. This program is widely used in many countries but has not been applied to the small basins in Vietnam because of data missing. In this study, scientific research on rainfall and detailed ground surface conditions was developed using Win-TR55 program for small watersheds. A watershed covering Ban Chat bridge on National highway 31 Dinh Lap district, Lang Son province, Vietnam was selected as a case study. The study shows a great potential of the Win-TR55 method to estimate the hydrograph for the small and medium watersheds in Vietnam.

Noi Thi Doan
Using HCM Method in Estimation the Highway Capacity and Recommendation Traffic Management for a Section of National Highway #5 - VietNam

The HCM method estimated the highway capacity base on the speed-flow relationship in the ideal conditions and other data collected in many state highways in the US, which support to define the capacity in conjunction with the level of services that a road or a highway facilities will adapt or could serve in the specific conditions of traffic, terrain, and geometry. In order to define the level of services and estimate the capacity of a specific roadway, the traffic and infrastructure data collection will be implemented firstly, then the highway will be divided by the sub-sections which have typical characteristics to estimate the capacity. This paper describes the data collection in the section of KM 55+582 to KM77+830 of National Highway 5 and briefs the analysis and estimation the capacity and level of services of study section base on the Highway Capacity Manual approach and recommends the improvement solutions.

Tran Trung Hieu, Trinh Xuan Lam
Green Infrastructure Modelling for Assessment of Urban Flood Reduction in Ho Chi Minh city

Urban flooding has become a severe problem in Ho Chi Minh City. Green infrastructure (GI) have been considered as a promising solution. GI is not only beneficial for urban flood reduction but also improved microclimatic conditions, landscape values. Recently, with the advancement of science and technology, the mathematical models have been developed and applied in various fields including urban flood. This paper presents the initial results of applying 2 urban water models, namely Tuflow and SWMM (Stormwater management model). The Tuflow mathematical model was used to simulate 2 dimensional (2D) surface model while the SWMM was developed for 1 dimensional (1D) surface and drainage water system. These models are later served in assessing the effectiveness of green infrastructure development in urban flood reduction. The models were developed at a specific study area (Tham Luong - Ben Cat Catchment) in Ho Chi Minh city. Results can be used for urban planning especially for urban flood management in Ho Chi Minh city.

Nguyen Hong Quan, Nguyen Duy Hieu, Tran Thi Van Thu, Matthew Buchanan, Nguyen Duc Canh, Mariana da Cunha Oliveira Santos, Pham Dang Manh Hong Luan, Tran Tuan Hoang, Huynh Luu Trung Phung, Khuu Minh Canh, Mitchel Smith
Review of Unmanned Aerial Vehicles (UAVs) Operation and Data Collection for Driving Behavior Analysis

In recent years, several innovative transportation data collection technologies have developed, including global positioning satellites, Bluetooth detectors, video detectors, lidar detectors, and radar detectors. While these technologies have been useful for data acquisition of both points (e.g., volume counts at a given location) and space data (e.g., travel time between two locations), they are still limited to gathering data on multiple vehicles over both time and space. This paper will examine the use of unmanned aerial vehicles (UAV) for transportation data collection. First, a literature review will be provided over the framework of UAV operations and current popular platforms with a focus on their capabilities, costs, and limitations. The review emphasis on the use of UAVs for speed behavior analysis, gap acceptance and merging behavior. Lastly, the challenges and consideration of UAV technologies for collecting traffic data in developing countries will be discussed with applications on Vietnam situations.

H. Q. Pham, M. Camey, K. D. Pham, K. V. Pham, L. R. Rilett
New cooperative approach between universities and enterprises, towards a reality urban planning. Lesson learnt from Nhon Ly, Quy Nhon city

In the process of development and international integration, the question of training associated with the practice has always been a challenge for all universities. Among the training, which requires a practical environment, the architectural formation in Vietnam is also in the process of transforming itself to adapt to the reality needs and international integration. From 2017, Hanoi Architectural University has been a pioneer in developing new international training model, in co-operation with schools of architecture in France and enterprise, which calls work-shop. The organization of the workshop is based on the cooperation between Hanoi Architectural University, the city authorities where the workshop takes place and an architectural cabinet. The workshop proposes to understand the complex relationship between space and time, the process and mutations of space at different scales and human influence on the transformation of the community. In this paper, by experiences from our work-shop at Nhơn Lý, Quy Nhơn province, we wish to introduce the advantages of the method in this new specialized training as well as pointing out the difficulties in the training process towards a reality urban planning.

Thai Huyen Nguyen, Thuc Trang Dang
Smart Monitoring for Urban Biodiversity Preservation

The rapid urbanization causes increased pressure on biodiversity, with dramatic consequences such as reduction of green areas, space fragmentation and species loss or transformation. Considering the importance of biodiversity for the quality of life in cities as well as for the biological and environmental equilibrium, cities should take great care for the protection and enhancement of the biodiversity. All the stakeholders of the city should be involved in the realization of this objective.The biodiversity conservation requires first of all monitoring in order to scan the current situation, to track the biodiversity evolution and to take the right measurements to stop the biodiversity degradation and even more to ensure its development. However, the biodiversity monitoring is very complex, because of the huge variety of parameters of the biodiversity as well as the long-term timescale. The recent developments of Smart Technology could be used for biodiversity monitoring in cities.

Thi Hai Yen Pham, Isam Shahrour, Ammar Aljer, Alain Lepretre, Celine Pernin, Sana Ounaies

Data mining and Machine Learning

A Daily Work Report Based Approach for Schedule Risk Analysis

The Critical Path Method (CPM) has been the dominant scheduling method for the past several decades. Most State Departments of Transportation (DOTs) in the U.S. currently apply CPM to estimate project duration for major and complex projects. The method, however, has limitations, and one of them is its poor ability to analyze schedule risks. While previous studies have identified various factors that cause uncertainties in schedules, the estimated duration from CPM is deterministic. To quantify schedule risks, the Program Evaluation Review Technique which uses three-point estimates for activity duration and Monte Carlo Simulation (MCS) based methods that assign uncertainties to work activities through the probability distributions of activity durations have been limitedly used in the industry. After running the simulation thousands of times, the probability distribution of the total project duration can be developed to assist risk analysis, such as determining a schedule contingency for the project. In current practices, the use of the MCS method is still limited due to various reasons. One of the most challenging issues is the difficulties in estimating the probability distributions of activity durations objectively. This study aims to leverage historical digital daily work report (DWR) data available in the DOTs’ databases to determine the probability distributions of the production rates of work activities then estimate the distributions of activity durations when quantities of the activities are provided. Since the DWRs record the daily accomplished quantity of each work item in the construction phase, the actual production rates of the work items can be calculated to obtain a more accurate and realistic duration estimate for a future project. DWR data collected from a DOT were used to conduct a case study that demonstrates the value of this new approach for schedule risk analysis.

Chau Le, H. David Jeong
A Deep Learning-Based Procedure for Safety Evaluation of Steel Frames Using Advanced Analysis

The biggest challenge of an advanced analysis is that it is time-consuming compared to an elastic analysis. This leads to the limitation of application of advanced analysis in complicated design problems such as optimization design and reliability analysis of structures where a very large number of structural analyses are required. To solve this problem, a deep learning (DL) based procedure for safety evaluation of steel frames is introduced in this study. An advanced analysis is used to capture the nonlinear inelastic behaviors of structures. Two DL models are proposed for estimation of the structural load-carrying capacity and evaluation of the strength safety of the structure by predicting the structural ultimate load factor greater or smaller than 1.0. A two-story space steel frame is studied.

Manh-Hung Ha, Quang-Viet Vu, Viet-Hung Truong
Prediction of buckling coefficient of stiffened plate girders using deep learning algorithm

This paper aims at introducing a new method to determine the buckling coefficient kb of the stiffened plate girders under pure bending using deep learning, one of the most powerful algorithms in machine learning. Firstly, output data kb is generated from eigenvalue buckling analyses based on input data (various geometric dimensions of the girder). This procedure is implemented by using the Abaqus2Matlab toolbox, which allows the transfer of data between Matlab and Abaqus and vice versa. After that, 2,200 training data are used to build the model for predicting kb using deep learning. Finally, 200 test data are used to evaluate the accuracy of the model. The results obtained from this model are also compared with analogous results of previous works with a good agreement.

George Papazafeiropoulos, Quang-Viet Vu, Viet-Hung Truong, Minh-Chinh Luong, Van-Trung Pham
Monitoring Pedestrian Flow on Campus with Multiple Cameras using Computer Vision and Deep Learning Techniques

This paper proposes a robust method for multi-camera person re-identification (ReID), which can accurately track pedestrians across non-overlapping cameras. Closed-circuit television (CCTV) are widely used to capture pedestrian movement in different places. By integrating CCTV with computer vision and deep learning techniques, trajectory of individual pedestrian can be efficiently acquired for analyzing pedestrian walking behaviors. Many existing ReID methods aim to extract discriminative human features to distinguish a person from others. Recent state-of-the-art performance is achieved mostly by obtaining fine features from each body part. However, these part-based feature extraction methods did not consider which parts are more useful for person ReID. Therefore, this paper proposes a weighted-parts feature extraction method, such that features of specific body parts are more influential to identity prediction. After comparing the performances of utilizing each part alone, several parts are considered more view-invariant and discriminative. Higher weights are then imposed on these specific parts to extract more useful human features for person ReID. Experimental results with videos on a college campus show that the ReID accuracy of our proposed method notably outperforms many existing ones.

Peter Kok-Yiu Wong, Jack C. P. Cheng
An Image Mosaicking Method Base on the Curvature of Cost Curve for Tunnel Lining Inspection

The paper proposes an image mosaicking method for tunnel lining inspection. The conventional methods only used the cost value of the pixel being processed based on similarity metric to estimate an image-matching location. To improve the image-mosaicking efficiency, the curvature metric has adapted to improve matching point accuracy. Experimental results for an actual tunnel demonstrate that the curvature measurement can select the precise matching points accurately for assisting defect inspection without depending on the speed of inspection vehicle.

Cuong Nguyen Kim, Kei Kawamura, Masando Shiozaki, Amir Tarighat
Application of Neural Network to predict the workability Parameters of Self-Compacting Concrete

The paper presents a new application of classical multi-layer perceptron neural network to approximate the parameters of fresh self-compacting concrete. The approximation is needed to determine the working parameters at construction site and can be used to estimate the components used at mixing station to achieve the desired concrete quality. A number of real field tests were conducted and six basic parameters were measured for each test. The numerical results showed the high accuracy of proposed solution.

Cuong H. Nguyen, Linh H. Tran, Khoa N. Ho
Development of Artificial Neural Networks for Prediction of Compression Coefficient of Soft Soil

Compression coefficient (Cc) of soft soil is an important parameter in solving many geotechnical problems. In this study, the main of objective is to develop an Artificial Neural Networks (ANN) for prediction of the Cc of soft soil. A total of 189 soft soil samples collected from the Ninh Binh – Hai Phong national highway project were used to carry out the laboratory tests for determining the parameters for modelling of which thirteen factors (depth of sample, clay content, moisture content, bulk density, dry density, specific gravity, void ratio, porosity, degree of saturation, liquid limit, plastic limit, plasticity index, liquidity index) were considered as input variables and the Cc was considered as a output variable for prediction models. This data was divided into two parts of training (70%) and testing (30%) datasets for building and validating the models, respectively. To validate the performance of the ANN, various methods named Mean absolute error (MAE), root mean square error (RMSE), squared correlation coefficient (R2) were used. The results show that the ANN are promising method for prediction of the Cc of soft soil. This study might help geotechnical engineers to reduce the cost of implement of laboratory tests and the time for construction.

Binh Thai Pham, Manh Duc Nguyen, Hai-Bang Ly, Tuan Anh Pham, Vu Hoang, Hiep Van Le, Tien-Thinh Le, Hung Quang Nguyen, Gia Linh Bui
Real-time detection of asymmetric surface deformation and field stress in concrete-filled circular steel tubes via multi-vision method

Aiming at the characteristics of full-field asymmetric surface deformation on the surface of concrete-filled steel tubular columns, a mark-free multi-vision measurement method is proposed, and the vision system structure, curved surface measurement principle, image acquisition, preprocessing algorithm and 3D point cloud reconstruction algorithm are illustrated. An image stitching algorithm is proposed to calculate the deformation radius of the asymmetric surface and the radius of curvature and its height of the largest deformation section. In the seismic test, the stereo vision system developed by the authors is used to automatically collect and process the three-dimensional deformation and field strain of the specimens. Besides, the three-dimensional point cloud reconstruction algorithm is proposed to realize the full-field three-dimensional deformation image reconstruction. The comparison results indicate that the multi-ocular vision measurement method can measure the deformation process of the asymmetric surface and the exact value of the full field strain, its accuracy meets the engineering requirement. The proposed method can evaluate the asymmetric deformation of the structure subjected to impact loads or vibration and provide real-time decision data for structural health monitoring.

Yunchao Tang, Kuangyu Huang, Lijuan Li, Xiangjun Zou, Wenxian Feng
A Possibility of AI Application on Mode-choice Prediction of Transport Users in Hanoi

Mode choice is a significant analysis of travel demand modelling. The selection of transport mode highly depends on the travel behavior of transport users, for instance, travel distance, trip cost, trip purpose, household income and so on. This study aims at investigating the possibility of applying Artificial Intelligent (AI) method to predict the mode choice through travel behavior survey data with a focus on Hanoi city - Vietnam. Firstly, travel interview survey was conducted with the involvement of 311 transport users at different land-use types. The study secondly applies the Ensemble Decision Trees (EDT) method to predict the mode-choice of transport users. Finally, the recommendation for a possibility of AI application on travel mode-choice is also proposed. The results of this study might beneficial for transport planners and transport authorities. The application of AI on parking demand forecast also contributes for the big data application on transport demand modeling.

Truong Thi My Thanh, Hai-Bang Ly, Binh Thai Pham
Machine learning based tool for identifying errors in CAD to GIS converted data

Recent advances in Geographic Information System (GIS) has made the storage, manipulation, and analysis of spatial data easier than ever. As a result, many public and private agencies have switched from the traditional Computer Aided Design (CAD) format to GIS for storing information about their infrastructure. The existing data stored in CAD therefore needs to be converted to GIS, and this process brings about at least two problems. First, GIS requires geographical coordinates that CAD data do not have, and the accurate projection and alignment of the infrastructure is not straightforward. Second, the original CAD data often possess errors such as overlapping lines, split lines, presence of text, and human errors, in addition to errors introduced during the conversion process. The goal of this study is to develop and apply a tool that can identify these errors and correct them automatically without human intervention. This study focuses specifically on the identification of the errors using decision tree learning. This tool can significantly reduce the time spent identifying errors on the GIS data obtained after the conversion. Finally, as a case study, this tool is applied to the wastewater system of the University of Illinois at Chicago campus.

Mohamed Badhrudeen, Nalin Naranjo, Ali Movahedi, Sybil Derrible
Development of 48-hour Precipitation Forecasting Model using Nonlinear Autoregressive Neural Network

Rainfall intensity has a significant impact on urban drainage infrastructures and the precipitation forecast therefore remains essential in urban areas. In this study, a prediction model using Nonlinear Autoregressive Neural Networks (NANN) was proposed to forecast 48-hour-ahead the rainfall intensity. The proposed NANN model, which is based on a precipitation data of five-year time series, was constructed and validated using various parameters such as Coefficient of Determination (R2), Root Mean Squared Error (RMSE) and Mean Absolute Error (MAE). The results exhibited a high statistical correlation between the outputs of NANN model and the measured data for 48 hour ahead prediction, i.e. R2=0.8998, RMSE=3.2909 and MAE=1.8672. This indicates that the developed model is very promising for precipitation forecasting and could contribute to improve the urban drainage systems.

Tien-Thinh Le, Binh Thai Pham, Hai-Bang Ly, Ataollah Shirzadi, Lu Minh Le

Building Information Modeling

Building Information Modeling Based Optimization of Steel Single-Plate Shear Connections Using Differential Evolution Algorithm

The conventional method that steel connections are still manually designed one by one is time-consuming. In this paper, a building information modeling based framework is proposed for automated generating steel connections. The differential evolution algorithm is used to seek the optimal solution of connection where the design variables are bolt diameter, bolts arrangement as well as plate dimensions. The objective function is the minimum cost of steel connection while the design constraints adopt the specification AISI/AISC 360. The optimized steel connection is then automatically created in the BIM model. A toolkit is developed to implement the proposed framework on Tekla Structures through open application programming interface (oAPI). The toolkit is applied for single-plate shear connections, which are the most popular connection type in steel buildings. An example of a steel frame is conducted to demonstrate the effectiveness of the proposed framework. The result of the example shows that the proposed framework can shorten the design time.

Tran-Hieu Nguyen, Anh-Tuan Vu
BIM application for the design consultant on the irrigation and hydropower projects in Vietnam

In the recent years, the construction industry has inherited great achievements from the rapid development of science and technology to improve labor productivity, increase the scientific quality, reduce risks and increase the efficiency of construction investment. Especially BIM applications are becoming an inevitable trend of the construction industry in the country thanks to the advantages of science, technology, economics and benefits in construction management. Vietnam is a developing country, so the construction industry has been and will continue to play a very important role in the country. Therefore, the application of BIM for the construction industry is also indispensable to reduce the risk and increase the efficiency of construction investment. However, the BIM application for the construction of irrigation and hydropower projects is still limited by the peculiarity and difficulty of human resource understanding on BIM technology. This paper presents some research results on application of BIM technology for the design consultant on the irrigation and hydropower projects in Vietnam.

Van Toan Tran, Huu Hue Nguyen, Tuan Long Chu, Lam Tuan Mai, Van Do Nguyen, Dinh Tai Nguyen, The Minh Ngoc Vu
BIM Adoption in Construction Projects Funded with State-managed Capital in Vietnam: Legal Issues and Proposed Solutions

It is claimed that Building Information Modelling (BIM) has been adopted in the construction industry in Vietnam since early 2000. However, in practice, this proves not to be the case, particularly in the context of construction projects funded with state-managed capital. Considering that such funding accounts for the largest market share in construction funded projects in Vietnam, further investigation is warranted. A preliminary survey reveals that the owners and other stakeholders of these projects are cautious of BIM adoption, primarily due to avoiding legal issues that may arise in such projects. In this context, this paper aims to explore the potential legal issues of BIM adoption and propose solutions for the stakeholders. The results will aid in avoiding the issues outlined, which can aid in promoting BIM adoption in Vietnam. Literature shows that the legal issues are not only applicable to Vietnam, but to other countries. To identify the legal issues which arise from BIM adoption in construction projects globally, a through literature review is carried out, where then a survey is performed with stakeholders of construction projects funded with state-managed capital in Vietnam. This then provides the opportunity to verify if the literature findings apply to Vietnam, as well as to discover new issues in a Vietnamese context. According to the survey results, the biggest legal issues for BIM adoption in construction projects funded with state-managed capital in Vietnam are; (i) no expenses system for BIM implementation available, so there is no source of funding for paying consultants/contractors for BIM; (ii) rights and obligations of stakeholders in BIM projects are not defined clearly in the relevant regulations, so there is a high risk of claims and disputes arising; (iii) no digital submission system available, thereby BIM models are not accepted, but hardcopy printouts used, leading to significant work of reviewing and verification of as-built documents. Solutions for these issues are generated and validated with focus groups, which lead to the suggestions of regulation alterations as well as revisions of contract forms/articles applied in construction projects funded with state-managed capital in Vietnam

Thuy-Ninh Dao, The-Quan Nguyen, Po-Han Chen
BIM-based innovative bridge maintenance system using augmented reality technology

A smooth transportation system plays a pivotal role in the development of a country since it enables rapid connect among industrial zones or territories. Especially bridges, which commonly has around 50 years’ service life, needs to be paid more attention to maintenance to keep it in a good service state. Nowadays most bridge has its own bridge maintenance system (BMS) but still bridge engineer is challenged by difficulty in term of store the damage records and repair history, as well as assess the current behavior of the structural system. This paper proposed an innovative BMS which using a schematic BIM-based information management system, collaboration with an automate inspection task using augmented reality (AR) device. According to preventive maintenance strategy, a data schema for BIM model was investigated. An integrated digital model is created to store, manipulate and share the inspection data and maintenance history. On another hand, the onsite inspection task is timely performed. The state-of-the-art lies on the versatile capacity in term of real-time data manipulate of AR device. Besides capturing feature, a chain of algorithms based on computer vision is embedded into the AR device, aims to enhance the precision and performance of inspection task. Right after, the technical damage report is fed-back to the management system and assessment model is discussed. A pilot application to an existing cable-stayed bridge is introduced, which is well applied for a year and show a good potential for bridge maintenance.

NgocSon Dang, ChangSu Shim
Perspectives on BIM Profession of BIM Specialists and non-BIM Specialists: Case Study in Vietnam

The adoption of Building Information Modelling (BIM) has been recently increasing within the Architecture, Engineering and Construction (AEC) industry. The current approach on adoption of BIM by the Vietnamese decision makers (e.g. government agencies and senior industry leaders) is primarily concerned with improving the adoption rate measured by the speed of diffusion and the number of adopters at basic implementation level such as 3D functions. This paper explores a different perspective on BIM adoption in Vietnam which has been neglected by proposing that the efforts of the decision makers should shift into regulatory supports and diffusion networks facilitating higher levels of BIM implementation such as 4D construction scheduling, 5D cost estimating etc. to confirm their long-term commitment to advanced BIM practices. Twenty-nine participants including BIM specialists and non-BIM specialists were selected from seven AEC organizations. Semi-structured interviews were employed for data collection. Key findings revealed general perceptions of the BIM profession such as “job insecurity”, “depleted motivation”, “BIM as supporting roles” and “BIM as new skill sets”. Recommendations for programs supporting BIM adoption are also discussed.

Ngoc Quyet Le, Michael Er, Shankar Sankaran, Ngoc Binh Ta
The contextual influence on Building Information Modelling implementation: A cross-case analysis of infrastructure projects in Vietnam and Norway

This paper compares Building Information Modelling (BIM) implementation in two infrastructure projects in two different countries to understand the contextual influence on innovation adoption in the construction industry. These two countries are Norway and Vietnam, which have different contexts in term of technology advance. In Norway, Bane NOR - the Norwegian railway authority decided to use BIM in the InterCity project which connects Oslo and nearby cities. InterCity is the first Norwegian large-scale railway project that utilizes BIM. The situation is similar in the Thu Thiem 2 bridge project in Vietnam. The design package of Thu Thiem 2 Bridge is a BIM pilot project of the Vietnamese government. Using qualitative interpretive case studies, this paper reveals the importance of the BIM champions in the implementation and different consequences derived from the project organization, technological context, and the focus of BIM use. The insights obtained from the comparison might be useful for increasing the BIM uptake and overcoming the barriers of traditional requirements for innovation. This is not only applicable to the Norwegian and Vietnamese infrastructure sectors but also for other contexts, which have limited BIM implementation experience.

Nam Bui
Application of BIM tools in technician training, a case of Ho Chi Minh City Construction College, Vietnam

In vocational training, keeping up with new technology is a challenge. Building Information Modeling (BIM) tools are now increasingly replacing traditional skills, which is irreversible advance in architecture and construction sector. This leads to changes in the curriculums of training courses, teaching and learning methods, especially in Technical Vocational education and Training (TVET). This article explores an application process of BIM tools in BIM Modeler or architecture technician training courses at Ho Chi Minh City Construction College as a case study, reflecting experience of change management toward new technology integration, its implication in and challenges for TVET’s methodology. The author also recommends that cooperation between industry and TVET in training is one of the most effective solution to solve human resource problem for construction sector.

Tung Lam Nguyen, Thi Xuan Nguyen
Bridge assessment for PSC Girder Bridge using Digital Twins Model

Bridge maintenance nowadays is no longer a “reactive activity” to the severe degradation or unexpected disaster. Aging and deterioration are inevitable, sometimes arises exponentially if maintenance strategy is neglected. Leading to structural failure, or worse case is the functional failure and seriously threaten the safety, interrupt the public transportation system. This paper proposes a new concept for preventive maintenance strategy for existing aged PSC Girder Bridge using a digital twin model. Digital Twins concept is mainly based on the use of parallel models: digital twin model (DTM), reality twin model (RTM) and mechanical twin model (MTM). DTM authoring is introduced using an integrated BIM mod-el, while RTM is verified by a reversed engineering surface model based on 3D scanning data. The RTM is generated continuously during bridge lifecycle in order to make a field-verified replica of the structure, aims to records all the bridge damage time by time. The mechanical twin model is derived directly from DTM through the interoperability of BIM model and adjusted by damage information from RTM. Discussion on bridge assessment model is induced based on the supposed analysis model and deterioration history, significant support for the decision making team in order to make a long-term strategy for bridge maintenance task.

NgocSon Dang, ChangSu Shim
Application of Building Information Modelling, Extended tracking technique and Augmented Reality in Building Operating Management

This paper presents a combination of Augmented Reality (AR), Extended Tracking Technique (ETT) and Building Information Modelling (BIM) to interact with building information in real-time on construction site. Using this method, we have programmed an application running in mobile device to help manage and operate the building facility systems. In this application, the building model and its information are stacked and augmented on the mobile device camera when projecting on the target image mounted on the building. ETT allows extending the object displayed on the screen, even when the mobile device camera no longer captures the target image. Based on this process, engineers can interact with the software to add, change the information needed of facilities on construction site, such as size, manufacturer, date of maintenance, date of replacement, device life cycle, etc.

Thanh Ban Nguyen, Anh Binh Tran, Manh Tuan Nguyen, Van Hoan Pham, Khuong Le-Nguyen
Protocol for Standard Contract Forms for projects involving Building Information Modelling (BIM) in Vietnam

This study will review international practices for BIM protocol and current contractual environment in Vietnam, interview participants in current pilot BIM projects on contractual practices, analyze possible conflicts between Vietnam Laws and the BIM Protocol for pilot projects (1057/QD-BXD), and recommend steps for future BIM protocols in Vietnam.

Nguyen Nam Trung, Dinh Tuan Hai
CIGOS 2019, Innovation for Sustainable Infrastructure
Dr. Cuong Ha-Minh
Dr. Dong Van Dao
Prof. Dr. Farid Benboudjema
Prof. Dr. Sybil Derrible
Dr. Dat Vu Khoa Huynh
Dr. Anh Minh Tang
Copyright Year
Springer Singapore
Electronic ISBN
Print ISBN