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2024 | Book

Recent Advances in Structural Health Monitoring and Engineering Structures

Select Proceedings of SHM&ES 2023

Editors: Le Thanh Cuong, Amir H. Gandomi, Laith Abualigah, Samir Khatir

Publisher: Springer Nature Singapore

Book Series : Lecture Notes in Civil Engineering


About this book

This book presents the select proceedings of the 3rd International Conference on Structural Health Monitoring & Engineering Structures (SHM&ES 2023). It covers the recent advances in the fields related to structural health monitoring, damage detection and assessment, non-destructive testing, inverse problems, optimization, artificial neural networks, and evaluation. This book is useful for researchers and professionals working in the field of health monitoring of engineering structures.

Table of Contents

Design Wave Crest Height on Submerged Coral Reefs

The topography of a submerged coral reef is divided into three parts: consisting of a flat reef, a fore slope steep reef, and a deep reef. A depth of a reef flat ranges from few to tens of meters. When waves propagate to the reef crest, most of them will break. This process is often complicated. The difference in wave variability in this reef type is a sudden change in topographic profile from hundreds of meters down to several meters in shallow water. According to many authors, after reef crest zone, there is the formation and development of infragravity waves, combined with short waves, leading to a significant in the mean water surface and a very large wave crest height on the reef flat. This paper presents the results of research on the distribution of wave crest heights on submerged reefs with small water depth (shallow water) by performing physical simulation in a wave flume. The research results will give the new coefficients that fit Weibull’s distribution to predict the wave crest height; this result contributes to appropriate choice of design wave crest height on submerged reef flat.

Tao Nguyen Quang, Dat Ho Duc, Dung Nguyen Trung, Bau Nguyen Van, Cuong Dinh Quang
A Solution to Measure Wave Overtopping on an Offshore Emerged Island

This paper describes the wave overtopping measurement on an offshore emerged island in Vietnam. This overtopping discharge measurement is very important in the analysis, evaluation, and design works on offshore emerged island, where the terrain is complex, has a steep front shelf, and cannot be applied to other applications formula in the standard to calculate the overtopping discharges. Overtopping discharge is measured using overtopping flume and overtopping tank assembled of wood and tarpaulin, which are easy to find and easy to carry. There are very few papers that publish solutions to measure overtopping in offshore emerged islands. Therefore, the results of the article are a set of data of overtopping discharge, wave height in front of the dyke, and manual measurement of overtopping waves on offshore emerged islands, which is a reference for designers, surveyors, and researchers.

Trung Dung Nguyen, Cao Tri Mai, Quang Tao Nguyen, Van Bau Nguyen, Duc Dat Ho, Manh Thai Do, Quang Hai Luu, Ngoc Thao Nguyen, Hao Nguyen, Van Hung Ha, Quang Cuong Dinh
Lateral Behavior of a Circular High-Damping Unbonded Fiber-Reinforced Elastomeric Isolator (UFREI)

In recent years, several devastating earthquakes have occurred, highlighting the importance of effective seismic isolation systems in reducing seismic hazards to structures. One of the most popular isolation systems is the use of elastomeric bearings, such as steel-reinforced elastomeric isolators (SREIs). However, the high cost associated with the use of thick connection steel plates and high energy consumption during manufacturing has limited their applicability, particularly for ordinary residential buildings in developing countries. In this context, a new type of elastomeric device, a fiber-reinforced elastomeric isolator (FREI), has emerged as a promising alternative. It can be applied to the structure in several ways: bonded (traditional), unbonded, and partially bonded. In unbonded conditions (UFREI), the isolator can be installed between the upper structure and foundation without any bonding or fastening. This, combined with the use of thin fiber layers in place of steel laminations, results in a reduction in materials costs and makes UFREIs a more cost-effective and feasible option. Furthermore, the dissipation energy without steel supports improves thanks to the shear load transferred through the friction generated between the isolator and the structure surfaces. This study presents an experimental investigation of the lateral behavior of a circular high-damping UFREI. The device has been subjected to cyclic shear tests considering different vertical pressures, with the results evaluated in terms of horizontal stiffness and damping ratio. The objective was to determine the impact of the vertical pressure on the final horizontal behavior of the device.

Gaetano Pianese, Gabriele Milani, Antonio Formisano
Modified Gradient-Free Proportional Topology Optimization for Heat Conduction Problem

In this study, the optimization of heat conduction is addressed by means of the gradient-free proportional topology optimization (PTO) algorithm. A pseudo-density field is introduced, and the thermal conductivity is determined by considering the solid isotropic material with penalization (SIMP) method. The numerical solutions of the heat conduction equation are obtained by employing the conventional finite element method. With the original PTO algorithm, the density of each element is considered constant, and the performance can be degraded by several numerical instabilities, e.g., one-node connected hinges and wriggle boundaries. In this study, a modified PTO algorithm is proposed to allow the interpolation of the density with discrete nodal values and thus remove the drawbacks of the original PTO algorithm mentioned above. The advantageous features of the modified PTO algorithm are highlighted through two numerical examples.

Youpheng Ly, Duy Vo, Jaroon Rungamornrat
An Approach for Plastic Hinge Length of RC Columns

The exact determination of plastic hinge length (PL) is critical in estimating the nonlinear behavior of structural components. However, due to the complexity of material nonlinearity, previous attempts to define and model plastic hinge length have resulted in large discrepancies. This paper presents a comprehensive approach to estimating plastic hinge length based on several criteria, including rebar strain profiles, compressive strain of concrete core and cover, curvature profiles, and damage observations. The approach was validated through testing on three large-scale reinforced concrete (RC) columns subjected to high axial load ratios and varying transverse reinforcement details. Results showed that different criteria must be used to separate plastic hinge lengths (PLs) due to large discrepancies, and that high compression loads can enhance PLs due to compressive yield strain of longitudinal reinforcement, compressive strain of concrete, and curvature profiles, but have a minor effect on PL based on tensile yield strain. The amount of transverse reinforcement had an insignificant effect on PL. This study establishes important discussions on the PL of tested columns.

Phu-Anh-Huy Pham, Chung-Chan Hung
A Fast Numerical Model for Describing the Bond Behavior of FRCM Reinforced System

The use of FRCM composites to reinforce building surfaces, particularly masonry structures, is becoming increasingly popular due to the compatibility and reversibility of the materials. The effectiveness of FRCM reinforcement is largely dependent on the bond between FRCM and masonry, which has been commonly investigated by shear tests, and various analytical and numerical models have been developed to reproduce the bond behavior during the tests. However, the existing simplified models often only consider the failure of either the fiber-mortar interface or the mortar-substrate interface and often ignore the cracking of the mortar. This paper proposes a mathematical model that takes into account both fiber-matrix and matrix-masonry interface failures and mortar matrix damage. The interfacial bond laws are characterized by jagged relationships to reproduce the degradation of the interfacial bond capacity during loading. The constitutive law of mortar is also characterized by the jagged shape to represent the decrease of tensile strength with cracking of the mortar matrix. The debonding problem can be described by an ODE system that can be solved by converting the BVP into an IVP by shooting method, and the solutions can be obtained quickly by a 2D bisection procedure. The results obtained by the current model are compared with existing experimental data and models, exhibiting good performance in predicting the global stress-slip curves.

Yu Yuan, Gabriele Milani
Effect of Longitudinal Steel Reinforcement on Shear-Flexural Behavior of Hybrid GFRP/Steel-Reinforced Concrete Beams

This paper presents the experimental results on the behavior of concrete beams reinforced with a combination of glass fiber-reinforced polymer (GFRP) and steel bars under shear-flexural bending. A total of four reinforced concrete (RC) beams were manufactured and subjected to four-point bending tests, with a shear span to equivalent depth ratio (a/d) of 3.65. Different ratios of longitudinal steel reinforcement, ranging from 0 to 1.01%, were analyzed to study the effect of the longitudinal steel reinforcement ratio on the shear-flexural behavior of hybrid GFRP/steel RC beams. Based on the experimental findings, the failure modes, relations between load and deflection, and relations between load and strains in materials were analyzed. The results obtained revealed the significant influence of the longitudinal steel reinforcement ratio on shear-flexural strength of the tested beams. With an increase in the steel reinforcement ratio, there was a corresponding decrease in the angle of the critical shear crack, the quantity of cracks, crack spacing, and beam deflections.

Hiep Dang Vu, Duy Nguyen Phan
Effect of Reinforcement Ratio on Time-Dependent Deflection of Hybrid GFRP/Steel Reinforced Concrete Beams

This paper presents an experimental study on the effect of the steel reinforcement ratio on time-dependent deflections in hybrid glass fiber-reinforced polymer (GFRP)/steel reinforced concrete (RC) beams (HGSRC beam). Three HGSRC beams and one reference GFRP RC beam were cast and tested under sustained load for a period of 180 days in varying environmental conditions. The longitudinal steel reinforcement ratio was varied to achieve a range from 0 to 1.08%. The results revealed that the steel reinforcement ratio had a remarkable impact on the time-dependent deflections of HGSRC beams. Moreover, the experimental time-dependent deflections of HGSRC beams were compared with theoretical values derived from design equations for fiber-reinforced polymer RC structures found in ACI 440.1R-15. The outcome showed that this design standard overestimated the long-term deflection of HGSRC beams. Also, a design method based on ACI 440.1R-15 with experimentally based adjusted time-dependent factors was presented for HGSRC beams. The predicted deflection values using the proposed method were found to be highly consistent with the experimental ones.

Hai Truong Quang, Nguyen Hung Phong, Hoan Nguyen Van, Viet Quoc Dang, Duy Nguyen Phan
Simulation for a Low-Rise Masonry House Using Seismic Isolator with and Without S-shaped Steel Dampers

In the recent years, due to the limitations of common isolation systems, there are new hybrid base isolation systems proposed, for instance, the hybrid device consisting of an unbonded seismic isolator and shape memory alloy, hybrid fraction yielding elastomeric bearing, and rubber bearing with slit damper devices. In this paper, to increase the dissipative energy capacity of isolation devices and decrease the superstructure displacement, the novel hybrid seismic system including seismic isolator connected with S-shaped steel dampers (SSSDs) is investigated, and a simplified model of that system is proposed. The numerical model of a low-rise masonry house with the simplified model of a novel hybrid system is established in ABAQUS. The simulations and the comparisons of a low-rise masonry house with and without a novel hybrid system are investigated under the earthquake action based on finite element method. The novel hybrid seismic system applied in a low-rise masonry house has more effective protection by adding SSSDs. It can be adopted as a reference to strengthen the mechanical capacity of seismic isolation system and supply the practical application in the field of civil engineering.

Kai Guo, Ahmad Basshofi Habieb, Gabriele Milani
Evaluating the Behavior of Architectural Pylons of Cable-Stayed Bridges

The cable-stayed bridge is considered a bridge with beautiful architecture. In recent years, engineers have researched using nontraditional bridge pylon types or adjusting the cable arrangement on the pylon and girder to enhance the architecture, uniqueness, and attractiveness. Constructing a highly aesthetic bridge pylon requires complex structural solutions and higher material costs. The bridge pylon is a significant compression and bending structure. The traditional resolution is straight-element pylon branches. However, curved pylon branches are increasingly applied to enhance aesthetics. The behavior of the curved pylon branches is much more complicated than that of the straight element, and so is the material cost. This paper studies the behavior of the curved pylon and compares them with the straight pylon in practical applications at Song Hieu cable-stayed bridge in Quang Tri province, Vietnam.

Nguyen Duc Thi Thu Dinh
An Improved Local Damage Model with Alternative Equivalent Strain for Quasi-Brittle Materials

This paper presents an enhanced model for damage analysis of materials that exhibit quasi-brittle behavior, with a recently developed alternative equivalent strain. The material state is represented by a damage parameter d ranging from 0 (intactness) to 1 (complete failure). Unlike conventional local damage models, the calculation of damage parameters takes into account both the fracture energy and the element characteristic length. This approach not only helps to alleviate the issue of mesh-dependency but also maintains low computational cost. For better modeling the failure behavior under mixed-mode loadings of quasi-brittle materials like concrete and limestone, where compressive strength is higher than tensile strength, two alternative equivalent strains are adopted based on the Ottosen and the bi-energy norm (bi-E) concept. It has been noted in literature that the evaluation of equivalent strain has influenced the prediction of the numerical model on the growth of the damage zone, especially when mixed-mode loadings are involved. By comparing the proposed approach with existing experimental data and other numerical models available in the literature, the accuracy and efficiency of this method are demonstrated.

Nhu-Quan Tran, Ngoc-Minh Nguyen, Quoc-Tinh Bui, Duy-Duc Ho
Structural Dynamic Analysis of Huqiu Pagoda Under the Influence of Earthquake

As an important masonry structure, the ancient masonry pagoda represents the history and culture of a country. Damage to the pagoda is mainly caused by earthquakes. Many experts and scholars have proposed lots of feasible schemes for the simulation analysis of masonry pagoda fragility, among which finite element numerical simulation is representative. At the same time, in order to help non-professionals quickly assess the collapse mechanism of masonry structures, manual limit analysis is also a fast and effective way. In view of this, this paper chooses an ancient Chinese masonry pagoda with an octagonal horizontal plane—Huqiu pagoda as a case. It performs pushover and nonlinear dynamic analysis simulations in the Abaqus which is the most common simulation software. The research selects the processed seismic waves of the 2008 Wenchuan Earthquake in China as the accelerogram. Manual limit analysis was also used as an auxiliary technique to compare the results of the finite element simulation. The research results depict that with the effect of the seismic waves, Huqiu pagoda develops bottom-up crack damage and activates the bending mechanism at the bottom.

Peixuan Wang, Gabriele Milani, Shengcai Li
Strengthening Precracked Post-tensioned Concrete Beams with CFRP Composites

The effectiveness of externally bonded carbon fiber-reinforced polymer (CFRP) systems in strengthening precracked concrete beams post-tensioned with unbonded tendons is not yet fully understood. Therefore, the objective of this experimental study is to partially fill this knowledge gap. The experimental program was comprised of four large-scale unbonded post-tensioned concrete (UPC) beams. One of the beams was loaded continuously to failure while the other three beams were first pre-loaded to simulate pre-damage. One of the pre-damaged beams was then loaded to failure while the remaining two beams were strengthened with four and six layers of CFRP composite sheets before being loaded to failure. The CFRP strengthening sheets have demonstrated its capability in restoring the functionality of the heavily pre-damaged UPC beam as well as enhancing the performance of the beam. By controlling cracks, carrying tensile stress and reducing beam stiffness degradation, the CFRP sheets significantly improved the behavior of precracked UPC beams in terms of crack, displacement and loading capacity when compared with the unstrengthened precracked beam. The performance of the FRP-strengthened precracked beams was even better than that of the unstrengthened beam without precracks in the ultimate phase.

Phuong Phan-Vu, Duong T. Tran
Damage Detection in Beam-Like Structures via Frequency Response Function

In this paper, a method is developed to detect the damage’s occurrence and location in beam-like structures using frequency response function (FRF). This method is applied to a steel beam whose damage is created by reducing the element’s bending stiffness of the beam. Additionally, this study is conducted in three steps of structural health monitoring. Firstly, FRF data is collected in undamaged and damaged states. Secondly, the occurrence of the damage is evaluated by the correlation coefficient of the FRF. Finally, a frequency response function-based index (FRFBI), which is used for detecting the damaged location, is proposed from the results of vibration analysis for the beam simulated by ANSYS software. This study indicates that the FRF-based damage detection method gives the results with high accuracy in both the occurrence and location of the damage.

Tran-De-Nhat Truong, Tan-Phu Vo, Hoang-Tang Phan, Thanh-Cao Le, Duc-Duy Ho
Novel Continuous Limit Analysis Modeling with Deformable Polygon Discretization

Limit analysis with continuous modeling is a quite suitable framework for analyzing the failure of soil-like material. Standard formulation comes up from the idea of finite element analysis. Usually, in this approach, the freedom of the degrees is assigned at the nodes. However, such a theory will limit the shape of the elements, which is only applicable to solving triangular mesh. In this paper, we propose a novel approach based on the idea of continuous modeling limit analysis. Here, all the variables are assigned at the centroid of the element, through which the approach can be easily extended to consider arbitrary polygon discretization. Assuming constant strain distribution, we first derive the geometric compatibility for arbitrary polygon deformable elements. Then, the flow rule for the plasticity in the elements is investigated. Implementing the proposed theory, the classical strip footing problem is solved as a benchmark study, with consideration of one triangular mesh and two polygon mesh. The results show that the load predicted by polygon mesh is overestimated, indicating the occurrence of the locking in the elements. However, the strain rate distribution predicted by the polygon mesh is more uniform.

Yiwei Hua, Gabriele Milani
Reliability Analysis for Tension and Compression Designs of Steel Truss Elements Using Vietnamese Codes

This study performs a reliability analysis to assess the probabilistic safety of truss members designed with Vietnamese design codes. Based on the investigations, the suitability of the load and the resistance factors currently specified in the design codes are examined. For this purpose, two truss structures are first designed using the load and actions code (TCVN 2737-2020) and the current design code for steel structures (TCVN 5575-2012). Monte Carlo simulations are then carried out for the design solutions. The results disclose that the reliability indexes associated with strength limit states are relatively close to the target index of 3.8, recommended in Eurocode. Overdesigned compression designs are found when the resistance factor of 0.9, currently specified in the national design code, is utilized. Hence, the compression bars are redesigned with modified resistance factors of 0.95. The reliability analyses are again performed, and the results reveal that the resistance factor of 0.95 is more reasonably applied.

Nhu Son Doan
Artificial Neural Network-Based Quick and Robust Technique for Ottoman Minarets’ Fundamental Frequency Prediction

Minarets are symbolic and indispensable parts of mosques in religious countries around the globe. Masonry minarets constructed during the Ottoman Empire are highly vulnerable to lateral excitations due to their brittle materials, slenderness, and distinctive shapes. After many minarets collapsed, preserving surviving ones in old Ottoman lands prone to earthquakes has become urgent. More importantly, determining the most vulnerable minarets to strengthen and maintain is a priority. Based on the earthquake spectrum of each region, the seismic vulnerabilities of minarets built on it can be warned effectively via the frequencies at some lowest modes. Instead of formulating the relationship between known geometrics and material information consisting of equivalent height, cross-section, inertia moment, Young’s elastic modulus, and mass density as considered in previous studies, this study presents an artificial neural network (ANN)-based approach to anticipate the fundamental frequency of Ottoman masonry minarets promptly. The measurements conducted on real minarets built around Bursa City (Türkiye) under ambient conditions are considered the output database of neural networks. Meanwhile, the available distinct parameters of minarets are selected to build the input dataset. As a result, the proposed ANN tool is practical and robust when the desired modal information can be estimated with high accuracy levels.

Quy Thue Nguyen, Ramazan Livaoğlu, Vu Truong Vu
Dynamic Analysis of Plate Under Moving Load on Dynamic Foundation

This paper presents the analysis of the dynamic behavior of the thin plate on the dynamic foundation subjected to moving loads. The stiffness of the foundation is considered variable. A numerical survey using the finite element method is applied to analyze the time-dependent dynamic equation of the plate. The numerical results describe the weakened foundation cases in practice and compare the difference between the dynamic and viscoelastic foundations.

Trong Phuoc Nguyen, The Tuan Nguyen
Application of a Machine Learning in Predicting Resistance Factor of Ring Foundation in Clays

Multivariate adaptive regression spline (MARS) is put forward as a unique equation to estimate the undrained resistance factor of a ring foundations rested in inhomogeneous and anisotropic clays. The previous study's numerical results are adopted as the MARS model's feeding data. The MARS equation's results have been evaluated with numerical data from previous numerical investigations. As a result, an excellent fitting between output values from the recommended equation and those from previous studies is obtained. The findings of this research can be a valuable tool for calculating the undrained resistance factor of ring foundations in inhomogeneous and anisotropic clays.

Dang Khoa Nguyen, Trong Phuoc Nguyen, Van Qui Lai
Assessment of Cause–Effect of Design Defects in the Implementation Phase of Construction Projects

Design-related risks negatively affect construction project performance, in which design defects (DD) are considered as one of the most important risks. Previous studies provide a diverse list of important factors related to DD. However, very few of these studies have examined the interactions between factors in a cause–effect relationship. Identifying individual factors based on their importance can make it difficult to propose mitigation or prevention solutions. This study provides the important factors related to DD based on their interactions by combining the rules of systems thinking for iterative cause loop–diagrams (CLD) and Decision-Making Trial and Evaluation Laboratory (DEMATEL). The research results showed that ‘poor design consultancy’, ‘lack of checking and approval during the design process’, ‘lack or error of data before design’, and ‘careless, irresponsibility’ are the main causes of DD. At the same time, DD greatly influence project efficiency, which is reflected in factors such as ‘rework during construction’, ‘slow completion of the project’, ‘cost overrun’, and ‘rework of design documents’.

Phong Thanh Nguyen, Linh Vu Ba Pham, Thu Anh Nguyen, Quan Khac Nguyen, Phuong Thanh Phan, Hang Thi Thu Le
Finite Element Modelling of Concrete-Encased Steel Columns Under Axial Compression

Concrete-encased steel (CES) composite columns are used extensively throughout the world due to their high strength, stiffness, ease of construction, and other benefits. Hence, this research focuses on analysis behaviour for CES composite columns under axial compression load. Test results of both high-strength concrete and steel were obtained for the simulation tests. The performance of the CES column is evaluated and analysed using a 3D finite element (FE) model. The influence of fibre fractions and transverse reinforcements on load-carrying capacity is mentioned in the study. The results show a significant improvement in axial compression by the difference in concrete strength, transverse reinforcement spacing, or steel fibre volume. Finally, the accuracy of the proposed model will be verified through force–strain curves.

Duc-Duy Pham, Hieu-Phuong Vu, Hoang-An Le
Lagrange Multiplier Method in Dynamic Finite Element Analysis of Frames with Nonlinear Multipoint Constraints Under Harmonic Loading

This research introduces the approach to finding the solution to the dynamic problem of the frames, loaded harmonic variation force, with nonlinear dependent multipoint boundary conditions using FEM. The establishing problem-solving model of frame, having a nonlinear functional equation of constraints, under variation force, requires mathematical technique to incorporate the nonlinear equations of constraints into the master dynamic equilibrium equation. For constructing a frame system's nonlinear FEM dynamic equation with nonlinear multipoint constraints, the imposition process is developed by employing the method of Lagrange multipliers. Using the method of Lagrange multipliers for converting a nonlinearly constrained problem, the nonlinear dynamic finite element system of the equation has been constructed. Solving technique for the FEM nonlinear dynamic equations of frames under harmonic excitation is constructed utilizing the Newmark time-integration technique combining the Newton–Raphson technique. According to the established incremental–iterative algorithm, the computing program has been written for solving the investigated problem. The testing results show the advanced possibility of the constructed algorithm in the analysis of the vibration of frames with a nonlinear functional equation of boundary conditions under a time-dependent load.

Thi Bich Quyen Vu, Ngoc Tien Dao, Thi Thuy Van Tran
An Empirical Study of Working Conditions on Construction Sites Affecting Productivity and Safety of Equipment Operators in Ho Chi Minh City, Vietnam

Productivity and labor safety when using machines and equipment during construction is one of the issues that contractors always focus on to bring production efficiency, ensure progress, and increase competitive advantage in their operations. This study aims to identify and evaluate the effects of working conditions on the productivity and safety of users of machines and equipment on construction sites in Ho Chi Minh City. Through the presentation of survey results and analysis, 172 questionnaires were collected. The results of the exploratory factor analysis (EFA) have shown five factors: (1) the organization of the construction process; (2) the personal factors of the operator; (3) the working environment at the construction site; (4) managerial and executive processes; and (5) the quality of machines and equipment. Construction contractors can use the results of this study to improve productivity and improve working conditions to ensure labor safety in the production process.

Nguyen Le Minh Long, Truong Van Luu
Multiple Decompositions for Modal Identification of Structures in the Time Domain

Blind source separation (BSS) has proven to be an effective approach for modal analysis of a structure using the output responses. The main challenge of this approach is to solve a smaller number of measured signals than operational modes (an underdetermined problem) and to estimate the exact number of operational modes automatically. Recently, tensor decomposition-based methods have attracted considerable attention for solving many complex situations in this field. This paper proposes a procedure based on multiple decompositions of covariance tensors constructed from vibration measurements for mode analysis in the time domain. Unlike a single decomposition, the proposed procedure uses multiple decompositions allowing the automatic selection of the exact number of these modes and the identification of modal parameters. The efficiency of the proposed procedure is illustrated by simulations and an experiment for different cases, even at different noise levels.

Duc-Tuan Ta, Dinh-Huong Vu, Trung-Duc Tran
Finalizing the Standard Bases for Determining Construction Investment Costs Using State Capital in Vietnam

Vietnam is in the process of industrialization and modernization. Along with economic, cultural and social development, construction investment activities are growing in both scale and quality. The formulation and management of construction investment costs are constantly improved in terms of content and calculation methods toward the direction of rigid management and control of costs, but also enabling the right to be proactive, improving responsibility, enhancing power of the person who decides to invest as well as the investor. In reality, however, there are many obstacles: lack of standard bases for determining costs, incomplete construction price and norm system, delay compared to market movements; unreasonable regulations on cost calculation, causing waste of investment capital, affecting project efficiency. The article aims to analyze the current situation of the bases for determining construction investment costs, establish groups of factors affecting this work, and conduct linear regression analysis to determine the factors that have great influence on this work. This is the ground for proposing solutions to finalize the bases for determining construction investment costs using state capital in Vietnam.

Dung Nguyen Thi Tuyet, Phu Tran Ngoc
Investigation of a Tuned Mass Damper with Piezoelectric Stack Energy Harvester Attached to an Undamped Primary Structure Under Harmonic Base Excitation

This paper develops the fixed-point theory for the optimal design of tuned mass dampers with piezoelectric stack energy harvesters under harmonic base excitation. The existence of two fixed points of the amplitude-frequency curve of the primary structure is proved. Based on the requirements for suppressing the vibration of the primary structure and enlarging the harvested power, the optimal tuning, damping, and resistance ratios are determined. Numerical examinations of the system with the obtained optimal parameters are performed, demonstrating a very good compatibility between theory and computation. More specially, it is shown that not only the vibration of the primary structure is effectively reduced but also a large amount of the harvested energy can be captured in the main resonance domain.

Vu Anh Tuan, N. N. Linh, Nguyen Van Manh, Pham Manh Thang, N. D. Anh
Nonlinear ANN Modeling for Predicting Ultimate Strength of CFST Columns

Artificial Neuron Network (ANN) applications are growing strongly in many scientific fields. Especially in structural engineering, ANN has been used to solve many issues. The datasets performed in those problems are preserved with the original data; general information is normalized if processed. In addition, the structure of the ANN applied is mostly multiple layers of perceptrons (MLPs) without giving precise information as to why MLPs are needed. This study as a contribution is transparent to the above problems using ANN. The problem is the ultimate strength prediction problem of the CFST circular columns with a dataset of 663 samples, including six continuous variables features. The ANN prediction model for the critical intensity of the above column type considers two more issues that have not been clarified, namely (i). Does the algorithm used, StandardScaler and MinMaxScaler, for data normalization affect the results of the predictive model? (ii). How do ANN structures have only one perceptron layer (Linear ANN—LANN) and ANN structures have multiple perceptron layers (Nonlinear ANN—NANN) with an equal number of units and does the different number of units affect the predicted problem above?

Tran-Trung Nguyen, Phu-Cuong Nguyen
Land Resource Management in Industrial Zones in Hanoi, Vietnam

Hanoi, the capital city of Vietnam, is one of the two major economic centers in the country. It has played a crucial role in the country’s economy, especially with the operation and development of industrial zones. As of 2022, there are eight industrial zones in Hanoi, covering a total area of over 1427 ha. These industrial zones have contributed significantly to the economic and social development of the capital city, attracting both domestic and foreign investment and creating numerous job opportunities. However, during the construction and development of these industrial zones, there have been many shortcomings, including ineffective use of land resources, wasting resources, misuse of land for the wrong purposes, violating space and environmental requirements, and negatively impacting the image and appearance of the capital city. One of the reasons for these issues is the ineffective land resource management in industrial zones. Therefore, there is a need for more effective and coherent solutions to managing this industrial zone. Through field investigations and surveys in Hanoi industrial zones, with the expert method, and research of published documents, the author has proposed some solutions for managing land resources in industrial zones in Hanoi, to save land resources, ensure efficient use, and promote sustainable development for industrial zones in Hanoi.

Le Thi Ai Tho
Italian Seismic Damage Prevention Policies for the Built Heritage: Efficacy and New Perspectives

Earthquakes that occurred in Italy in the last 50 years—in particular the most recent seismic events which affected Northern and Central Italy in 2012 and 2016–17—have shown the high intrinsic vulnerability of existing structures. Many historical structures and old town centers suffered partial or total collapse, even in the presence of seismic improvement interventions. This fact underlines, on the one hand, the wrong definition of the seismic hazard that in most cases largely exceeded the design one, and on the other hand, the limitations of seismic preventive policies prescribed by the Italian building code, especially for listed buildings. Furthermore, sequences of shocks with similar magnitude are typical of Italian earthquakes. In these conditions, namely seismic multi-events conditions, the existing buildings suffered progressive and severe damage, overcoming the life safeguard and collapse limit states defined by the national prescriptions. This condition results in a high level of risk for operators acting in the post-earthquake phase, since aftershocks may cause further collapses of already damaged buildings. Severe damage was observed also in almost all the historical listed buildings. In the seismic multi-event context, especially in Central Italy, the damage evolution brought to the complete loss of historical structures. Italian regulations prescribe very limited seismic retrofitting works for listed buildings, that cannot even cope with the first shock of the seismic sequence. In light of this, new seismic preventive policies should be adopted, at least in areas with moderate-high seismic hazard, to safeguard people’s lives and avoid the loss of cultural heritage. Moreover, strong shock sequences, occur frequently in Central Italy; thus, new preventive policies would be required to limit damage accumulation and, therefore, reconstruction costs.

Maurizio Acito, Martina Buzzetti, Claudio Chesi, Gabriele Milani
A Model for Predicting the Bearing Capacity of the Soil–Cement Columns Using the Soil Resistivity

Soil–Cement Column (SCC) is a semi-rigid structure of which quality could not be thoroughly assessed by non-destructive tests such as Impact Echo, Impulse Response, Impedance Log, Parallel Seismic, etc. Unlike concrete piles as rigid structures, the problem of SCC is due to its relatively low stiffness and inhomogeneity. The reason in the process of mixing at the site, re-using the in-situ disturbed soil, and conducting to the deep zones of the soil stratum, the product faces so many risks of questionable quality. Because the structure is semi-rigid, the method of using electrical resistivity (ER) in geophysics is suggested. This article deals with an experimental model in which an axisymmetry SCC with a sufficiently wide soil medium is created for measuring the ER, having electric probes installed in a Wenner and Schlumberger configuration. By tracing the change of electric resistivity (ER) within the structure having different stiffness, and comparing the ER map of the homogeneous soil medium before and after cemented treatment, between non-defective and defective structure, etc., the change in mechanical properties of the structure is predicted quantitatively. The bearing capacity of the structure could be then estimated by applying formulas in traditional calculations. The results of the bearing capacity of a soil–cement column calculated would be compared to those predicted by the artificial neural network (ANN) and tests in a small-scale model. The model which uses ER in predicting the bearing capacity of a semi-rigid structure indicates a quantitative tool in geotechnical engineering.

Tham Hong Duong
Evaluation of Buried Shallow Pipes Under Various Loading Conditions

Underground infrastructure system is an essential component for urban because they enable to ensure the normalcy of citizens. Buried pipes and culverts are the most structures used for sewage, water supply, communications, cable, or oil/gas…They are designed to bearing both the external load such as superimposed earth loads of embankments, surcharge load from the surface as well as internal load like water pressure (in water supply pipe); heat transfer (in cable pipe). In addition, the serviceability of a pipeline depends greatly on its stability. This paper presents an evaluation of pipes under various loading conditions as live load on surface and compaction of backfill soil. The analytical results used as a tool for prediction factors may cause pressure of pipelines under various loading conditions.

V. T. T. Giang, D. N. Trang
Analysis of Free Cable Vibration with Material Damping for an Applied Cable-Stayed Bridge

Monitoring cable tension has recently been an important problem in assessing the condition of cable-stayed structures. Many factors that affect cable tension, such as flexural rigidity, sag, lay angle, and complicated boundary conditions, were studied. However, the influence of damping has rarely been considered. In this paper, the mathematical model of the damped vibration of the cable has been studied to find the effect of material damping on tension. The experimental results from vibration data of cables in the cable-stay bridge are used to verify the relationship between frequency, damping, and tension. This study aims to use vibration techniques to increase accuracy in tension determination and condition assessment of cables.

An Huynh-Thai, Cong Hoa Vu, Toan Pham-Bao
Calculate Lightweight Concrete Aggregates for Constructing Bridges

In recent times, the application of lightweight materials in structural engineering, including bridges, has become a common practice. Besides possessing features like thermal insulation and a longer curing period, lightweight concrete provides a significant advantage in the form of reduced weight compared to normal concrete. Consequently, a more lightweight structure translates to an increased span length, reduced seismic effects, smaller abutments, and piers. This article focuses on the calculation of a lightweight concrete mix specifically for bridge applications and examines the efficiency of internal forces in reinforced concrete bridge girders that utilize lightweight concrete. These results can be utilized as a reference when undertaking bridge construction ventures in Vietnam.

Quoc Long Hoang, Trong Chuc Nguyen
Analyse Deformation of Ground During Excavation Process in Basement Building Construction—A Case Study in Ho Chi Minh City

In modern cities, high-rise buildings were built more and more with limited land area. Therefore, the basement is the way out to increase underground space to solve that above matters. However, the deformation and stabilization of soil around need to be controlled during the excavation process in basement construction. Besides that, decreasing the water table is also the reason to make deformation of underground. The focus of this paper is to analyse the changing of soil around and find the best way to control during construction process in Ho Chi Minh area.

Phu-Huan Vo Nguyen, Trung-Nghia Pham Dinh
The Effectiveness for Installations and Strengths of the Application of Cold-Formed Steel SupaCee Sections

Cold-formed steel structures have been progressively used in structural buildings with the application of typical channel sections. The cold-formed channel sections are prone to be instable due to the small thickness and large web, and this leads to the occurrence of the buckling phenomenon at the early stage wasting the material expenditure. Therefore, stiffeners have been added to the web of this section to increase the sectional stability to create a section termed SupaCee. The paper will investigate the capacities of such steel channel and SupaCee members due to compression or bending by using the direct strength method. The obtained results are the basis to estimate the capacity improvements of SupaCee members compared to those of channel ones. Installation effectiveness of the innovative SupaCee sections is also analysed on the basis of technical reports from the manufacturers.

Ngoc Hieu Pham, Thi Trang Luu
A Few Problems with the Electric Charging Station Design for Vietnam’s Urban Road Network

Many different types of electric cars are currently in circulation on the urban road network in Vietnam. However, there are currently a few problems with the urban road network of electric charging stations constructed in Vietnam’s urban areas, including the location layout not being connected to traffic planning and urban infrastructure planning, the station design charging in accordance with foreign standards, not taking into account Vietnam’s traffic conditions, and the inappropriate fire safety. The lack of standards and technical requirements for the construction of electric charging stations in the urban network in our nation currently presents a significant disadvantage to the implementation of policies aimed at converting electricity use. The authors’ article presents some criteria for the design of electric charging stations suitable for urban road network, current urban traffic flow characteristics in Vietnam.

Quoc Long Hoang, Trong Chuc Nguyen, Hoai Thu Nguyen
Impact of Sea Embankment Works in Cat Hai Island District (Hai Phong City, Vietnam) on Hydrodynamic Fields and Sediment Transport

Coastal construction works have a specific impact on hydrodynamic fields. The MIKE 21/3 model is used to simulate the scenarios before and after the construction work (area of 752 ha in Cat Hai district, Hai Phong city). The simulation results show that: after the construction, there is no impact leading to the change of the water level regime in the study area; the flow direction changes quite a lot after construction, especially in the east of the calculating area. Due to the narrowing of the water area outside the Lach Huyen estuary, the flow in both spring and ebb tides is markedly increased in magnitude and spatial. Amongst the three modelled rivers—Lach Huyen, Cam, and Lach Tray rivers—the sediment from Lach Huyen and Cam rivers is the most direct and robustly influenced. In the case of construction, there is not much difference between the dry and the rainy season scenarios. However, it is necessary to pay attention to reinforcing the cape area with embankments, underground breakwaters, etc., to ensure the area’s stability under the impact of extreme conditions such as storms and intense monsoons.

Tu Tran Anh, Tien Pham Van, T. Vu-Huu
Effect of Curing Regimes on Compressive Strength of Lightweight Concrete Using Fly Ash Cenopheres

This paper presents the research results of the influence of different curing regimes on the compressive strength of lightweight concrete using fly ash cenospheres (FAC) and multicomponent binder system (cement combined with mineral additives) to make lightweight concrete structures with low bulk density and high compressive strength. The experimental results show that the curing regimes influence significantly on the development of the compressive strength of concrete. The steam curing and autoclave regimes improve the compressive strength of concrete at both early and late age, and at early age, concrete strength can also reach about 80% of the final strength value after steam curing and autoclave curing. In particular, when the samples are treated with autoclave curing (210 ℃, 2 MPa), the intensity is higher than that in other curing regimes (steam curing (70 and 90 ℃, RH ≥ 95%) and standard curing (27 ± 2 ℃, RH ≥ 95%)). The highest compressive strength was nearly 80 MPa, approximately 20% higher than that of the standard curing samples.

Thanh Mai Pham, Viet Hung Le, Hong Khoa Pham
Study on the Effect of Re-Burning Temperature of Rice Husk Ash on Its Activity to Use as an Active Additive for Portland Blended Cement

In this study, Cautre rice husk ash (RHA) was burned at various temperatures from 500 to 700 °C at different retention period to survey the activity of RHA to use as an active additive for Portland blended cement (PCB). The experimental results show that RHA calcined at 500 °C in 30 min has higher puzzolanic activity and improves compressive strength of cement. The RHA sample calcined at 700 °C in 30 min has suitable chemical properties and fineness according to TCVN 8827:2001, but it decreases the cement strength. The heat-treated RHA samples improve normal consistency and reduce the setting time of cement when comparing to non-heat-treated RHA one.

Ngoc Dung Ta, Thanh Mai Pham, Thi Xuan Lan Tran
Improving the Behavior Reinforced Concrete Frames Made of UHPC Using the Metallic Vertical Shear Link

This paper investigates the behavior reinforced concrete frames of the Ultra-High Performance Concert (UHPC) using the metallic vertical shear link. Accordingly, a metallic vertical eccentrically braced frame (VEBF) shear link with a shear mechanism is explored in the UHPC. Accordingly, improving the behavior of the RC frame with double VEBF is investigated. Although the VEBF system pertains suitable behavior and is easily replaced after, it is difficult to construct. Its replacement does not affect the building severability since no gravity load is applied to the system. The finite element models are applied to investigate the behavior of moment-resisting frame made of UHPC and conventional concrete strengthened with metal vertical shear link. The accuracy of the prosed results is compared with the reported experimental test. The numerical results indicated that adding the VEBF to the RC frame enhances the ultimate strength, stiffness, and energy absorption of the RC moment-resisting frame. Also, it prevents hinge formation over the main column.

Chung Nguyen Van, Ali Ghamari
Kinetic Pyrolysis Model for the Thermal Degradation Process of Wet Wood Subjected to Fire

This study compares the kinetic pyrolysis model to the thermal model in Eurocode 5 (EN 1995-1-1:2004 in Eurocode 5: design of timber structures—part 1: general rules and rules for buildings. European Committee for Standardization, Brussels, Belgium, 2004 [1]) regarding the thermal profiles, mass transfer, and charring depths to represent the thermal degradation of wet wood under the standard ISO 834-1 (ISO 834-1:1999 in Fire-resistance tests—elements of building construction—part 1: general requirements. Int Organ Stand, 1999 [16]) fire curve. The numerical model is applied to some examples of 2D and 3D thermal models using a user subroutine called Umatht in Abaqus (Abaqus in User manuals v. 6.14, Dassault systems. Simulia Corp., 2016 [12]): cross-laminated timber (CLT) panels, dowelled connections between steel and wood, and panel. The acquired results demonstrate that in comparison with the model in Eurocode 5, the kinetic (pyrolysis) model is better able to simulate the thermal deterioration process that occurs in wet wood when exposed to fire.

T. T. Tran, Viet Phuong Nguyen
Effects of Coconut and Polypropylene Fibers on Properties of Mortar Containing Fly Ash as a Partial Replacement for Sand

This study investigates the influences of coconut and polypropylene fibers (PP) on the performances of mortar containing fly ash as a sand replacement material. Fiber-to-cement ratio is 0.3%. Fly ash to fine aggregate ratios are 0, 10, and 20% by volume. Flow, compressive strength, flexural strength, and total shrinkage of mortar are studied. Based on the results, the flow of mortar containing fibers is decreased. The decreased flow of mortar with coconut fibers is more than that of mortar with PP fiber. The compressive strength of mixtures is slightly enhanced by using fibers. Only polypropylene fiber shows more effectiveness to enhance the flexural strength of mortar. The use of fly ash as a fine aggregate decreases the flow and increases the compressive strength of mortar. Total shrinkage of mortars is significantly reduced by using both coconut and polypropylene fibers. Overall, the mortar with polypropylene fiber shows better performance than coconut fiber mortar, especially mortars with fly ash as a sand replacement material.

Nguyen Thi Bich Thuy, Warangkana Saengsoy, Vu Minh Hieu, Pham Duc Han, Phan Thuy Tram Anh
Size-Dependent Steady-State Response of Surface-Loaded Half Plane with Microstructures

This study investigates the microstructural effects on the steady-state dynamic response of a plane-strain half plane excited by harmonic surface loads. The theory of couple-stress elasticity is adopted to simulate the response of materials with microstructures. A closed form of a general solution is derived via the Fourier integral transform method. All unknown coefficients are determined analytically with the aid of boundary and remote conditions. To verify the formulation and implemented solution procedure, results are then compared with available benchmark solutions. Established solutions form a basis for investigating the fundamental role of material microstructures on predicted response and handling contact problems.

Salinporn Leewatchanakul, Wipavee Wongviboonsin, Jaroon Rungamornrat
An Improved Local Damage Model with Adaptive Mesh Refinement for Quasi-Brittle Materials

In this paper, an adaptive mesh refinement scheme is utilized to further enhance the local damage model (shortly as the local model) for quasi-brittle materials, for e.g., concrete or limestone. The novelty here is twofold: (i) introduction of an alternative equivalent strain for a local damage model and (ii) incorporation of the proposed model with adaptive mesh refinement. Compared to non-local models, a local damage model is advantageous in term of low computational cost. By taking the characteristic length of element and the material fracture energy into account during calculation of damage parameter, the issue of mesh-dependency being inherent to traditional local models is here mitigated. Based on the so-called bi-energy norm concept, the equivalent strain can be split into tension and compression parts to better model the behavior of materials that exhibit higher compressive strength than tensile strength, like concrete and limestone. Here, the split operator is based on the Mazars model for concrete, resulting in an equivalent strain that has only one parameter for calibration (instead of four parameters as in the Mazars model), yet the accuracy is sufficient. For efficient computation, adaptive mesh refinement is conducted, i.e., the mesh is only updated (refined) in the vicinity of the damage zone. The damage parameter, representing the deterioration of a material point from its initial state to total failure on a scale from 0 to 1, can serve as an indicator for mesh refinement as well. The refinement task is conducted such that each quadrilateral element is divided into four new elements. The issue of hanging nodes is avoided by the employment of polygonal elements instead of the traditional four-node quadrilateral based on Lagrange shape functions. The accuracy and efficiency of the proposed model are demonstrated and analyzed via various numerical examples, in which comparison with results available from experiments and other numerical methods is studied.

Manh Van Pham, Minh Ngoc Nguyen, Tinh Quoc Bui
Machine Learning Models to Predict Buckling Strength of Steel Beams According to TCVN 5575:202X

The draft Vietnamese steel structure design standard TCVN 5575:202X is nearly issued with many changes compared to the current version. Some recent research results have been updated in this version, for example, section classification and plastic stress distribution. Even so, determining the critical moment for lateral-torsional buckling according to TCVN 5575:202X is still quite complicated with many calculation steps. This paper proposes a new approach to predict the critical moment of steel beams using machine learning. Firstly, a large amount of data is generated in which the inputs are the effective length as well as the section dimensions, while the output is the corresponding critical moment values that are determined using the procedure described in TCVN 5575:202X. There are two separate datasets, one for training model and the other for testing model. Several machine learning regression algorithms, including support vector machine, random forest, artificial neural network, and adaptive boosting, are employed to build the prediction model. The performances of these models are compared through three metrics: MAE, RMSE, and the coefficient of determination. The obtained results show that the random forest outperforms the three remaining models for this task. A numerical example is then conducted to confirm the applicability of machine learning for predicting the buckling strength of steel beams. The value predicted by the random forest model is < 2% different from the value calculated by theoretical formulas.

Trung-Kien Nguyen, Anh-Tuan Vu, Tran-Hieu Nguyen
The Performance of a Defective Steel Beam in a Semi-rigid Beam–Column Connection

This article aims to study the performance of the steel beam working in semi-rigid beam–column connections or joists in high-rise buildings. The major target of the paper is to establish a dimensionless equation for evaluating the performance of a defective steel beam in which the criteria for local and general instability of the structure are considered according to the specific regulation. Steel material has higher strength, stiffness, and ductility and proves to be the best choice in many various meanings; however, when studied quantitatively such material with defects in terms of slenderness (i.e., a cause for the effect of local buckling), or over exceeded vertical loadings (overall buckling, and lateral instability), the performance has been proved to be quite different. Local buckling is due to slenderness of flanges and web; this effect makes the structure deformed and lowers the frequency. This would be a base for diagnosing such a structure in high-rise buildings. By analyzing a steel beam with a specific configuration of the ratios of flanges and the webs, subjected to different cases of loadings, a dimensionless equation for evaluating the performance of the steel girder is created, then the same approach is applied to the specified beam withstanding the local buckling (due to slenderness) and overall buckling (due to Euler’s condition of the critical load). Some results about the importance of factors contributing to the performance of a steel beam, lateral displacement due to warping effect, local buckling for flanges and web, etc., are found. By recognizing the change in natural frequencies of response, together with a comparison in flexural capacity in terms of the ultimate moment, and the damage indices, a rapid decrease in the performance of a local buckling defective one is recognized.

Tham Hong Duong
Evaluation of Stiffness Loss Indicators Using Displacement Influence Lines for Homogeneous Beams

In this work, the simple beam and continuous beam with two spans—two popular types of beam structures—were examined under various conditions to assess the loss of stiffness of beams subjected to moving loads with the use of the influence line of displacement approach. The goal of this study is to identify damage (occurrence, position, and degree of stiffness deterioration) in beam structures using influence line displacement diagnostics in conjunction with finite element modeling to mimic structural behavior. A variety of damage evaluation indices are produced to assess the damage in the assessed beam based on the displacement influence line data that was received from the simulation results of various failure scenarios. Four indicators, including DAC (displacement assurance criterion), CC (correlation coefficient), RMSD (root-mean-square deviation), MAPD (mean absolute percentage deviation) are chosen for evaluation in this study. Based on displacement influence line data, the beam's damage evaluation indicators can locate parts with reduced stiffness. Results show that the displacement influence line approach works for diagnosing single damaged beams. However, in the case of multiple damaged elements, the approach necessitates a large number of displacement access points.

Tuan Minh Ha, Ngọc-Thuy-Vy Dang, Duc-Duy Ho, Trong-Phuoc Nguyen, Saiji Fukada
Intrinsic Damping of Cable Stay Bridge—Full-Scale Field Testing and a Regression Model for Prediction

Stay cable vibration excitation such as vortex, galloping, or rain–wind induced may lead to the risk of fatigue of the bridges’ structure components and then reducing the service life of the bridge. Most of the design criterions proposed by International Standards on stay cable bridges are based on the Scruton number (Sc), the important parameter directly related to the stay cables intrinsic damping. Furthermore, depending on parameters of system and environment, the prediction of accurate value of the cables’ inherence damping is difficult. The field testing is generally considered as the most suitable evaluation approach of the cables damping values. In this paper, we present the in-situ damping tests campaign performed on a new built stay cable bridge in Vietnam with large diversity of stay cable characteristics. Based on the measurement data, a regression mathematical model is proposed for damping prediction as the function of frequencies, cable lengths, unit weighs, and cable inclinations. The coverage verification shows that the proposed model can represent well the damping characteristic of the stay cables on the bridge.

Nguyen Phuong Duy, Tran Duc Lan
Modeling the Pressuremeter Test by FEM × DEM Approach

In geotechnical engineering, site investigation and soil properties determination are important tasks. For this purpose, several approaches have been developed so far. Among them, the pressuremeter is one of the most essential testing processes. This test is useful and widely applied for the estimation of soil and weak rock characteristics. Besides in-situ and/or laboratory experiment works, numerical attempts have been also developed to correctly simulate and predict the behavior of pressuremeter test made of granular soil. This is usually done by using finite element method (FEM) with (non-)associated plastic constitutive law or pure discrete element method (DEM). However, both methods have some drawbacks. First, describing the discrete nature of granular soil is not simple even with advanced constitutive law. Second, it seems a great challenge for DEM when accounting for a large number of real-grain sizes in a single simulation. To overcome these limitations, in this paper, we use multi-scale modeling, intimately combining FEM and DEM to capture the mechanical behavior of granular soil during pressuremeter test. The simulation consists of macro-discretization by finite element method and a discrete element method (DEM)-based constitutive model. To define this new constitutive model, a volume element (VE) composed of 2D-circular particles is used. The VE is then compressed to isotropic stress condition before performing the pressuremeter. Thanks to the multi-scale results, macro–micro-behaviors have been analyzed, providing micromechanics insight into macroscopic behavior of the process. The obtained results revealed that several microscopic parameters controlled and are the origin of granular soil behavior.

Trung-Kien Nguyen, Thanh-Trung Vo
Mobile Lidar for Road Surface Monitoring: A Case Study of an Integrated AU20 Lidar

Lidar is a new trend in data collecting in surveying in general and in the monitoring field. However, lidar operated on a car solution for road surface data collecting is a quite new platform. The paper is an assessment of using lidar for this kind of purpose. In the study, an AU20 lidar is used on a car platform with three different speeds including 25, 30, and 40 km/h to scan about 3 km of asphalt surface road. The scan data were processed by Copre software using PPK processing mode. The base station is an i90 GNSS receiver. Output data were compared to a conventional method with an ATB4 auto level. The results study indicated the efficiency of AU20 lidar solution with vehicle platform when the time of scan process is around 10 min and about 17 min in total including preparation. The most surprising is the accuracy when comparing the asphalt road surface elevation from point clouds to that from the level method. The maximum differences in elevation are 10, 21, and 19 mm for 25, 30, and 40 km/h speeds, respectively. The standard deviations are 3.0, 6.5, and 7.5 mm for three car speeds.

Ngoc Quang Vu, Hoa Pham Thi Thanh
Bifurcation Analysis of Shear Band for a Cohesive-Frictional Granular Material with DEM-Based Constitutive Model

In classical geomechanics, bifurcation theory and stability analysis are powerful tools for predicting the behaviour of complex system, such as geomaterials. While previous bifurcation analyses have been obtained using classic constitutive models (i.e. non-associated plasticity, hypoplastic or strain-softening plasticity models), in this paper, bifurcation analysis for granular material sample has been carried out with a new DEM-based constitutive model. This new constitutive law has been developed by the author in recent years and has been demonstrated to correctly take into account the discrete nature of granular material. During this work, we focus on the case of biaxial test aiming to discuss the feature of formation of shear band and non-homogeneous deformation of granular sample. Moreover, the onset of the shear band is predicted by the evaluation of the determinant of the acoustic tensor (Rice criterion). We show that the evolution of Rice criterion is in agreement with the future shear band predicted by the simulation. However, the shear band orientation is affected by the geometry of the problem.

Trung-Kien Nguyen, Thanh-Trung Vo
An Implementation of Finite Element Method for Determining Free-Surface Seepage Problems

Free-surface determination is an important issue of groundwater seepage analysis in unconfined problems as this surface may not be prior known. Therefore, this is defined as a very highly non-linear problem, especially when including the effect of unsaturation into considering the hydraulic conductivities of soils. This study is an implementation of finite element method for solving this problem. Besides, it also considers the effect of unsaturation on the hydraulic conductivities using a popular model. Next, numerical experiments have been conducted through a range of soil types and mesh sizes. The conclusions are that two types of soils, namely fine and coarse ones, do not have a significant influence on the number of iterations. Moreover, the mesh fineness that is represented by a ratio called the area ratio (AR) has been examined to see whether the outcomes are stable or not. The percentage of the average element size over the entire calculated area is 0,1% or finer is acceptable in terms of accuracy.

Thi Tuyet Giang Vo, Vo Trong Nguyen
A Novel Finite Element Model Updating Application Based on Experimental Vibration Data

This paper proposes a Finite Element (FE) model updating method using structural dynamic characteristics. The method is performed on a slab bridge. The FE bridge is modelled in MATLAB, considering the minimum number of support points for boundary conditions and the maximum meshed element size. The prototype of the slab bridge is set up in the laboratory. The experimental vibration data is collected using fifteen accelerometers, National Instruments (NI) equipment, and a laptop. The dynamic features of the experimental slab bridge, for example, natural frequencies and mode shapes are analysed using vibration data and used as an objective goal for updating the FE model. The updating approach is based on novel nature-inspired optimization algorithms optimization techniques like Particle Swarm Optimization (PSO), Firefly Algorithm (FA), Genetic Algorithm (GA), Cuckoo Search (CS), and Flower Pollination Algorithm (FPA). The modulus of elasticity, support distances, and plate dimensions are considered to be updated parameters. The experimental results imply that the updated parameters are reasonable and have a clear physical meaning.

Quoc Bao Nguyen, Duong Huong Nguyen
Effect of Curing Conditions on the Mechanical Properties and Permeability of Concrete Incorporating Sulfate-Resistant Admixture

Concrete needs an adequate time and proper curing condition to reach its potential strength and durability. Curing is a vital procedure that keeps concrete at a sufficient moisture content and temperature throughout the hydration of the cementitious material, allowing the required qualities of concrete to develop. This paper presents an experimental investigation on the influence of different curing conditions, i.e., drying, water, and curing with seawater on the mechanical properties and permeability of concrete containing a sulfate-resistant admixture up to an age of 28 days. Two concrete mixtures with and without sulfate-resistant admixture were prepared with a constant water-to-cement ratio of about 0.37. It has been found that the inclusion of the sulfate-resistant admixture is effective in enhancing the compressive and splitting tensile strengths as well as the impermeability of concrete at 28 days, regardless of the curing conditions. Additionally, the results suggest that the concrete should be cured by immersion in water for up to 28 days, rather than other curing conditions, in order to obtain the best performance before being exposed to other environments such as drying or marine environments.

Bao-Loi Dang, Long The Doan, Nguyen Van Hai, Duy Nguyen Phan, Hung Nguyen-Xuan, Viet Quoc Dang
Damage Detection and Quantification in Cantilevered Beam Using Modal Strain Energy and Genetic Algorithm

Structural health monitoring is known to be a demanding area of research which has its applications in large-scale load carrying structures like bridges, aircraft, automobiles, offshore platforms, and submarines. Numerous optimization-based algorithms are suggested for damage detection in literature. Evolutionary optimization algorithms require minimum number of modal parameters as inputs and these methods are also capable to deal with incomplete data and noise. Therefore, genetic algorithm is preferred over deterministic optimization algorithms in the current study. Using genetic algorithm-based optimization techniques has the drawback of being computationally expensive because it requires estimating the fitness for the entire set of solution space at the end of each iteration of GA. In the current study, a multistage methodology is used to reduce the GA solution parameters. Modal analysis was performed on both undamaged and damaged structures. Damage was localized using the ratio of change in modal strain energy (MSECR) in order to reduce the solution space for the GA. An evolutionary optimization algorithm based on changes in frequency and mode shape is used in order to calculate the true damage percentage. Numerical studies of cantilever beam have been carried out to validate methodology. Numerical studies indicate that the multistage approach is more computationally feasible, robust, and rapidly convergent.

Muhammad Shoaib Ur Rehman, Naveed Akmal Din, Muhammad Wasif Khan
Structural Behavior of Hollow High-Strength Concrete Beams with Different Size Reductions

This article aims to combine the plasticity and damage material models to predict the crack patterns of a concrete structure. The load–deflection behavior will be focused on investigating, as well as the changes in the shape of the hole. To achieve this goal, two concrete beams, one solid and one with a central hole were fabricated and made a four-point bending test to evaluate and compare their flexural behaviors. To prove the reliability of the experiment results and the presented model, the numerical simulation was used to verify the experimental results and provide a basis for analyzing proposed cases. The results show that the combination model in this study can be a useful one for structure cracking analysis.

Van Trinh-Do, Minh Tran-Luan
A Two-Step Approach for Damage Identification in 3D Concrete Frame Using Damage Location Assurance Criterion (DLAC) Method and Cuckoo Search Algorithm

This paper introduces an efficient method to detect the damaged elements in a 3D concrete frame. First, Damage Location Assurance Criterion (DLAC) based on the changes in natural frequencies is selected as the objective function which is denoted to solve the inverse problem in damaged indicator. The calculation of this objective function value is determined through the model updating which using the finite element method. Second, Cuckoo search algorithm is utilized to minimize the objective function errors with design variables relating to the extent of identified damaged elements. And final, a 3D concrete frame with the different damaged case is used to consider the trustworthiness of the method introduced. The results obtained demonstrate that the computational advantages of the method presented to precisely determine the extent and location of multiple structural damages.

Thi Thuy Linh-Nguyen, Van Ho-Thanh, Minh Tran-Luan
Analysis the Behavior of Deep Beam by ABAQUS

Reinforced concrete (RC) deep beams are one of the most common types in civil buildings in Vietnam, especially in high-rise buildings for the transfer beams. For the deep beam, the assumption of a flat cross-section, the related equation for calculation are not suitable and the stress diagram is not linear. This leads to differences in calculation and design compared to regular beams. Making clearly the behavior of deep beams and the differences with the regular beams is necessary. Nowadays, the analysis of deep beam is conducted based on two cases: (1) span-to-beam depth ratio L/h; (2) shear span-to-beam depth ratio a/h. However, these values differ according to different standards. This paper investigated many different cases of span/beam depth ratio corresponding to two cases of load position. The results show that the definition of deep beam using the span-to-beam depth ratio according to Eurocode standard and the shear span-to-beam depth ratio according to ACI 318 is suitable.

Viet Phuong Nguyen
Evaluation of the Software’s Reliability in Solving the Buckling Problem of the Cold-Formed Plain C-Section Member Bending About Its Asymmetrical Axis

The elastic buckling moment of the cross-section of the thin-walled member is the value to be determined during the calculation of the direct strength method (DSM), which is mentioned in design standards AISI S100 and AS/NZS 4600. This value is calculated by software such as THIN-WALL-2, CUFSM 5, and GBTUL. To obtain a reliable buckling moment, software needs to be tested not only at the design stage but also continuously during use. There are methods of checking software output, including checking against theoretical solutions or comparing the outcomes of software with each other or with those of reliable software. Applying the second procedure, the article compares and evaluates the calculation results of THIN-WALL-2, CUFSM 5, and GBTUL on 16 Lysaght cold-formed C-sections subjected to bending about the asymmetrical axis, then compares them with those of ABAQUS. The content of the comparison includes the main buckling mode, the elastic buckling moment, the half-wave length, and the signature curve. Research shows that the calculation results of THIN-WALL-2 are in best agreement with those of ABAQUS.

Huy Hoang Vu, Cao Hung Pham, Quoc Anh Vu
An Enhanced Particle Swarm Optimization Algorithm for Design Problem

In this work, particle swarm optimization (PSO) algorithm is improved, called EnPSO, for design truss system. First, a factor is added into PSO to create two phases (local and global search). A distribution function using Lévy flights is employed to exploit the narrow search space. The results obtained from investigations of EnPSO algorithm are compared with several well-known candidates and original. Finally, a structure with multi-loading consisting of two constraints is designed to validate the accuracy of this method.

Thanh Sang-To, Minh Hoang-Le, Thanh Danh-Tran, The Vi-Huynh, Thanh Cuong-Le
Da Lat’s Threatened Urban Heritage: Causes and Solutions

In Vietnam, heritage cities are increasingly attracting tourists and are a good economic source. However, the overheated tourism development leads to difficulties in preserving urban heritage, gradually reducing the urban heritage and losing the attractiveness of the cities that have such heritage. Da Lat is a city with many heritages located on the western plateau in the central region of Vietnam that is facing such a situation. Although Da Lat is on the way to becoming a heritage city, the hot development of mass tourism along with rapid urbanization has caused the number of urban heritages of Da Lat to continuously decrease. The article focuses on analyzing the causes of the destruction of Da Lat’s urban heritage as well as learning case studies from cities that preserve the heritage. In the article, the authors made an outstanding number of field trips and conducted several interviews with experts who are very knowledgeable about the conservation of Da Lat urban heritage to draw out the main causes leading to the decline of the Da Lat urban heritage fund. From there, the authors propose solutions to preserve the urban heritage of Da Lat in a sustainable way.

Nguyen Nguyen Thi Hanh, Trang Nguyen Thi Nhu
A Novel Process to Improve the Performance of Metaheuristic Algorithms

Metaheuristic algorithms occupy the randomisation since there is no guarantee, they always provide reasonable solutions. The algorithms only can confirm global solutions to optimisation problems after a fair amount of computations. It means that a series of computations for comparison is inevitable. Thus, the world still beholds introductions of more advanced algorithms with much more excellent performance. This paper introduces a novel technique to increase the performance of the metaheuristic algorithms for optimisation problems. It is called push-process, which is a straightforward and powerful alternative for improving metaheuristic algorithms. In this paper, two well-known metaheuristic algorithms (e.g. particle swarm optimisation—PSO and bat algorithm—BA) are executed to apply the push-process. In this study, several numerical benchmarks are utilised to validate the effectiveness of the proposed technique. All numerical tests in this research are programmed by MATLAB software.

T. Vu-Huu, Thanh Cuong-Le
Numerical Investigation of Transverse Compressive Behaviour of Kevlar Fibre Under Ballistic Impact at the Microscopic Scale

Kevlar woven fabric is a complex structure. Its microstructure is comprised of a lot of yarns consisting of hundreds of fibres. In addition, the experiment of this material is high-cost and very complicated. Thus, the microscopic behaviour has not been well investigated. This paper studies the transverse compressive behaviour of the fabric under ballistic impact at the microscopic scale using a multi-scale numerical model with only six primary yarns within the impact zone that is modelled at the fibre scale. It is highlighted that by this model, the transverse deformation of fibres is observed. Furthermore, the fibre–fibre and fibre–projectile interactions are also described.

Q-Hoan Pham, Anissa Khalifa, T. Kanit, A. Imad
Recent Advances in Structural Health Monitoring and Engineering Structures
Le Thanh Cuong
Amir H. Gandomi
Laith Abualigah
Samir Khatir
Copyright Year
Springer Nature Singapore
Electronic ISBN
Print ISBN