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About this book

This book highlights current research and developments in the area of Structural Engineering and Construction Management, which are important disciplines in Civil Engineering. It covers the following topics and categories of Structural Engineering. The main chapters/sections of the proceedings are Structural and Solid Mechanics, Construction Materials, Systems and Management, Loading Effects, Construction Safety, Architecture & Architectural Engineering, Coastal Engineering, Foundation engineering, Materials, Sustainability. The content of this book provides necessary knowledge for construction management practices, new tools and technologies on local and global levels in civil engineering which can mitigate the negative effects of built environment.​

Table of Contents

Frontmatter

Element Level Bridge Inspection in the U.S.—Challenges for Assessing Specific Distress Type, Location and Progression

Collapse of the Silver Bridge over Ohio river between West Virginia and Ohio in 1967, which killed over 40 people, highlighted the need of conducting frequent safety inspections. Consequently, the Federal-Aid Highway Act of 1968 was passed that required the U.S. Secretary of Transportation to establish the National Bridge Inspection Standards (NBIS) to ensure the safety of the traveling public. The Act directed the States to maintain an inventory of bridges in the Federal-aid highway system. This Act was amended several times and the Federal Highway Administration (FHWA) revised its regulations to develop the current version of the Standards. The National Bridge Inspection Standards provide guidelines on the types of bridges that are required to be inspected, inspection frequency, qualification of bridge inspectors, and documenting observations and maintenance of bridge inventories. As per the Standards, bridge components are classified into three major groups: bridge deck, superstructure, and substructure. A rating between 0 and 9 is assigned to these three components based on their condition at the time of inspection. Due to several drawbacks associated with the NBIS rating procedures, in early 1990s, element level bridge inspection method was introduced. The AASHTO Manual for Bridge Element Inspection provides the procedures and guidelines for element level inspection. This manual provides two element classifications: National Bridge Elements (NBEs) and Bridge Management Elements (BMEs). Also, highway agencies can define and incorporate additional elements into their databases as Agency-Developed Elements (ADEs). Four levels of condition states are defined with guidance statements for inspectors. This article describes the evolution of bridge inspection procedures, challenges for effective use of data, and the required changes to address specific conditions for improving inspection data accuracy, quality, and usefulness.

A. R. M. H. B. Amunugama, U. B. Attanayake

A Multi-scale Model for Predicting the Compressive Strength of Ordinary Portland Cement (OPC)

Realistic prediction of mechanical properties and performance of the Ordinary Portland Cement (OPC) is frequently required, as the OPC plays the key role in concrete material that is broadly used in construction industry. This paper aims to predict the compressive strength of hydrated cement paste by a multi-step approach incorporating thermodynamic and multi-scale models in two subsequent steps. In step 1, the thermodynamic model developed in PHREEQC platform was amended and extended to predict the volume fraction of hydration products. In the consequent step, the multi-scale analytical model was developed to predict the compressive strength of the cement paste. This step comprises three hierarchical levels, initiates the model at nano-scale to the way up to micro-scale, which are sequentially C-S-H globule, C-S-H foam (includes capillary porosity) and the cement paste (consist of hydration products, porous and unhydrated cement). In this approach, as a key concept, the formation of calcium silicate hydrate (C-S-H) was distinctly considered in low and high-density states to an accurate prediction. The results obtained from the previous step was implemented to the subsequent step, and by the end of each step, the predictions were successfully verified with the experimental data reported in the literature. The comparison of model outcomes suggests high predictive capability of the model; however, the proposed model can be possibly valid to the conditions used herein, and to generalize the model, further verifications are highly recommended, left for the future work.

S. Krishnya, Y. Yoda, Y. Elakneswaran

Construction of Working Platforms on Expansive Soils Using Recycled Concrete and Stabilizers: A Case Study

Expansive clay soils are distributed worldwide, and are a source of damages to infrastructure, building foundations and roads due to its low strength, high compressibility and high level of volumetric changes. Due to excessive soil movement, uplift pressure can induce swelling pressure on foundations and shrinkage of clay can result substantial foundation settlements. In order to mitigate such adverse behaviour on structures, underlying clay needs to be improved prior to supporting the structural foundations. This study investigates the capability of enzymatic cement stabilization with recycled concrete to improve soil stability in the application to building foundations. Firstly, a series of experiments was conducted to characterise the Expansive clays obtained from the construction site. Then the experiments were performed on the basis of stabilized soils to investigate the improvement in strength and hydraulic behaviour of expansive soil. Stabilizing mix design obtained from lab tests was applied to construct building foundation on in situ clay base. Structural monitoring of the constructed foundation reveals minimal displacements during drying and wetting periods across 10 years after construction. Results from the current study will assist to derive a new standardized approach for constructing capping layer for buildings and roads using recycled materials and innovative soil stabilization methods.

H. Karami, D. Robert, S. Costa, F. Tostovrsnik, B. O’donnell, S. Setunge

Damage Assessment of Geopolymer Aggregate Concrete Using Numerical Modeling

Production of alternative aggregates is an area of study that is contributing to achieve the goal of producing sustainable concrete. However, a thorough understanding of the material is required prior to its application in construction for sustainable practice. While laboratory experiments can facilitate the understanding of new material, it is always challenging to use lab tests for damaged response evaluation and in particular failure assessment of its applications. State-of-art numerical modeling approaches with advanced material modeling can facilitate minimizing those challenges when they are calibrated/benchmarked using measured data. This study investigates for a suitable modeling approach to capture the damage response of a new material (i.e. Geopolymer) based coarse aggregate (GPA) concrete. Modeling was conducted by adopting the standard continuum modelling method. Unconfined strength test was simulated by considering Concrete Damage Plasticity (CDP) model in an explicit platform. Laboratory experiments such as stress-strain tests and compressive strength tests were also performed to calibrate and benchmark the results from the numerical model. The effect of mesh sensitivity has been identified in the outcome of damage prediction for GPA concrete. Results from the verified numerical models have been related to assess the permeability degradation of GPA. Outcomes from the study are important to predict structural/damage response using the new Geopolymer based aggregate concrete and facilitate the evaluation of structural response under loading.

C. Seneviratne, D. Robert, C. Gunasekara, M. Wimalasiri, D. Law, S. Setunge

Quantification of Benefits of Soil Stabilized Pavement Layers for Sustainable Road Infrastructure

The service life and performance of pavements depend mainly on the quality of the materials used for construction. Naturally available materials such as soil, stone aggregates, sand etc. and some of the processed materials like bitumen are conventionally used for road construction. But they are depleting fast and results in higher procurement and processing cost. Therefore, alternative materials such industrial wastes, chemical products are considered for road construction. If these materials can be suitably utilised in highway construction, the pollution and scarcity of aggregates problems may be partly reduced. In the present study, a soil stabilizer produced by the Stabilroad is investigated for its application in pavement layers. The Stabilroad stabilizer should be used along with cement which can be mixed with the existing soil. This makes the pavement layers to have good compressive strength as well as flexible and waterproof. The StabilRoad allows the agencies to stabilize different soils and build roads using locally available soil without the need to extract new material from the mines. Different dosages of cement and Stabilroad are mixed with the available soil and their geotechnical characteristics are evaluated. The focus was to study the strength characteristics of untreated and stabilized soil samples by Unconfined compressive strength and resilient behaviour under cyclic loading conditions using cyclic triaxial test procedure as per AASHTO T-307 protocol. Typical Red soil was collected for present study investigation. The optimal dosage of cement and stabilizer was determined based on laboratory studies. The strength properties of stabilized soils were determined at optimum dosage. Using the results, alternative pavements were designed according to IRC guidelines and validated using KENLAYER software. The critical strains were found to decrease with stabilized subgrades as compared to natural soil as subgrade. A cost comparison analysis is carried out to assess the financial benefit of using the Stabilroad. The reduction in virgin aggregates consumption due to the use of stabilized pavement layer is presented. Typical Red soil was collected for the present investigation.

Dheeraj Bonagiri, Veeraragavan Amirthalingam, Srinivas Vallabhaneni

Impact of Contractor’s Overhead and Profit Factor on Price Fluctuation Calculated Using CIDA Price Fluctuation Formula

The inevitability of price fluctuations is highly demanded topic all over the world. When it comes to the construction industry, the fluctuations of the prices of the construction inputs i.e. materials, labour, plant and equipment should be particularly studied since they are biasing to the contract sum in millions, billions range in major projects. The Price Adjustment (PA) technique is introduced by the Construction Industry Development Authority (CIDA) [formerly Institute of Construction Training and Development (ICTAD)] known as the “CIDA formula method for adjustment to contract price due to fluctuation in prices” has a constant of 0.966 based on a 15% fixed profit percentage according to the derivation of the formula. But the contractor’s overhead and profit margin vary widely and neither be fixed for all projects nor for each and every construction contractor. Generally, it can vary according to the type of construction project and according to the contractor. Hence, the price escalations rendering from the CIDA formula are not the true fluctuations for a particular project or a contractor. Therefore, this study was carried out to investigate the degree of accuracy of the CIDA price fluctuation formula method compared to the conventional method with the aid of an automated spreadsheet. Furthermore, it discusses and interprets the deviation of the price escalation generated from CIDA formula and the actual modified CIDA formula for contractor’s profit percentage. As interpreted by the study, it shows the true escalation to a high-end contractor should be lower than the current escalation calculated by the CIDA formula for a particular project whereas low-end contractor should be paid more than the current amount calculating from the CIDA formula. Therefore the current CIDA formula is not giving the true price escalation in point of view from the contractor’s profit percentage.

A. S. Samarakoon, L. S. S. Wijewardena

Assessing Applicability of Structural Measures for Enhancing Flood Management in Sri Lanka

Floods can be identified as one of the most devastating natural disasters all over the world which brings a considerable amount of social, economic and environmental impacts. Therefore, it is important to focus on adequate knowledge, strategies and decision makers in order to prevent these floods from becoming disasters. Different measures are taken in order to respond to the prevailing disaster situations and those measures can be categorized as structural measures as well as non-structural measures. Among them, substantial attention should be paid for adopting structural measures for flood mitigation. Structural measures can be defined as different types of facilities which are permanently constructed with the aim of reducing potential risk at an event of a flood. The study provides literature synthesis addressing the importance of structural measures in flood mitigation process, different types of structural measures and their impact regarding Sri Lankan context.

Rusiru Ernst, Udayangani Kulatunga, Pavithra Rathnasiri

Experimental Study on the Flexural and Shear Behaviour of Precast Prestressed Hollow Core Slab

In general, the total cost of the building is mainly influenced by the self-weight of structural members. In particular, the self-weight of the floor slab is a key parameter which restricts its span. The hollow core slab (HCS) is being developed as an alternate to the conventional solid slab and results in self-weight reduction up to 50%. However, the reduction in the cross-sectional area increases the flexural deflection, which can be overcome by prestress technology. In this study, the flexural behaviour of precast prestressed HCS made of Styrofoam, with 10 m span, was examined experimentally. Two specimens were tested, one with screed (topping) concrete and other without screed concrete. The influence of screed concrete on the flexural and creep behaviour was investigated. It is found that the screed concrete reduces the flexural and creep deflection significantly. The applicability of HCS system to industrial buildings was investigated by adopting a service load as per Indian standard, IS 875 (Part 2): 1987, and subsequently found that the HCS satisfies the code requirements related to strength and serviceability (deflection and crack). Additionally, it was observed that the voids significantly influences the shear capacity of precast prestressed HCS.

R. Sagadevan, B. N. Rao

Gas Diffusivity Based Characterization of Stabilized Solid Waste from Kurunegala Open Dump Disposal Site

Open dumps are complex ecosystems with respect to Greenhouse Gas (GHG) emission which occurs as a consequence of anaerobic decomposition of organic substances typically available in Municipal Solid Waste (MSW). Subsurface soil conditions (e.g. soil texture, structure) and atmospheric boundary conditions (e.g. wind, temperature) are the major key factors which affect the water retention characteristics, gas diffusivity, and hence the subsurface transport of GHGs. In this study, we characterized the stabilized “soil-like” fraction sampled from an open dumpsite located in Kurunegala, Sri Lanka to investigate subsurface landfill gas (CO2) transport behaviour. The MSW, collected at 2.5–5 m depth was screened to separate the stabilized “soil-like” fractions and proportioned into two groups (0–4.75 mm, 4.75–9.5 mm) for the particle-size based characterization. Soil-gas diffusivity (Dp/Do, where Dp and Do are gas diffusion coefficients in soil air and free air, respectively) and soil–water characteristic (SWC) of the stabilized waste were measured and parameterized using existing and modified parametric models. The results revealed that the investigated material exhibited two-region porosity (i.e., inter-aggregate pore region and intra-aggregate pore regions) which, in turn, affected the water retention and gas transport properties. We further experimentally investigated CO2 gas transport originated from a point source buried in medium bench-scale emission tank under the dry condition and the observed subsurface methane profiles were simulated using the multiphase transport simulator TOUGH2-EOS7CA. In addition, potential effects of atmospheric boundary controls, wind (1.5 and 3 ms−1) and temperature (26 and 34 °C), were also examined based on a series of controlled bench-scale experiments using bench-scale emission tank interfaced with a wind tunnel at the dry condition. Results showed the pronounced effects of particle size and wind and, to a lesser degree, of temperature on soil-landfill gas migration.

M. Shanujah, T. K. K. Chamindu Deepagoda, M. C. M. Nasvi, A. K. Karunarathna, V. Shreedharan, G. L. S. Babu

Investigation of the Relationship Between Densities Versus Mechanical Properties of Sri Lankan Timber Species

The aim of this study was to investigate the relationships among wood density, modulus of rupture (MOR), modulus of elasticity (MOE), compression parallel to grain (CNP) and compression perpendicular to grain (CPG) in 32 timber species grown in Sri Lanka. Defects free stem section from each timber was taken at the breast height and samples were prepared according to BS 373: 1957 standard. The tests for mechanical properties were performed through the Universal Testing Machine (UTM 100 PC). Linear Regression Analysis was done for interpreting the effectiveness of the relationship in wood density with other mechanical properties (MOR, MOE, CPG, CNG). The relationship between wood density and mechanical strength properties were analyzed by regression models. Wood density showed strong positive relationship with CPG and MOR. Results in the regression test revealed a significant relationship (P = 0.001) among wood density and other mechanical properties such as MOR, MOE, CNP and CPG. These results can be used for developing effective timber classification system in Sri Lanka.

C. K. Muthumala, Sudhira De Silva, K. K. I. U. Arunakumara, P. L. A. G. Alwis

A Guide for Structural Health Monitoring of Buildings in Sri Lanka

Structural Health Monitoring (SHM) of a building, also known as a ‘Structural Audit’, is a method of ascertaining the performance of the building in its operational condition. SHM has been in existence for a long time under different names. In the past, it was practice for a professional to be called upon to make a structural assessment of the structure if the building was about to change hands, had to undergo structural changes, or even to observe distress points. However after few building failures around the world especially the collapse of an eight storied building in Dhaka in 2013, the trend (especially in Asia) changed and building operators found the need for a structural audit at a regular basis. Major multinational operating in south Asian countries has made it mandatory to check the structural stability of the buildings (especially factory buildings) on an annual basis in order to have a continued business. SHM of a building is a specialised job, and an experienced professionally qualified civil/structural engineer is usually tasked with this function. This paper is structured according to the three main categories of SHM (1) Observation and Non Destructive Testing (NDT) under operational condition; (2) analysing data to check performance of the structure under the present condition; and (3) recommendations and remedial action, if required. In Sri Lanka, it has been a practice to issue a report on visual observation of the building. This paper seeks to set out a methodical manner in conducting inspections for SHM within the Sri Lankan context.

R. C. Loganathan

A Review on Mechanical Properties and Morphological Properties of Concrete with Graphene Oxide

This paper contains a comprehensive review carried out on the literature of performance of cementitious composites of Graphene oxide (GO) and cement. During the past decay, various types of Nanomaterials introduced to the cement to achieve the durability and higher strength. For the substantial improvement of the construction industry are using Silica fume as a mineral admixture. This gives very high and ultra-high strength concrete. Even though cement–silica composite has high performance, intrinsic brittleness nature of cement is a limitation for some application which can overcome by using nanomaterials. There are few common nanomaterials which, are used for concrete Nano silica, nano titanium, carbon nanotube (CNT), carbon fiber and graphene. As a composite material, chemically oxidized graphene which is graphene oxide is extensively used in favour of its bulk production and good dispersion properties. Graphene could combine into the cement paste or mortar and strengthen the bonds of the cement hydrates. As a result, the essential properties of cement and especially its tensile and compressive strength could be improved. The Graphene Oxide and Ordinary Portland Cement (OPC) composite are normally produced by dispersing GO sheets in water. For this purpose, did not use surfactant, dispersant or stabilizing agents. The compositions produced by adding GO at the time of mixing the cementitious materials, course and fine aggregates and water. Research works show that very low quantity of GO is needed to improve flexural strength of an OPC matrix. It also improves the ductility and reduces the risk of catastrophic damage due to the extreme loads. The addition of GO improves the pore structure of concrete and decrease the total porosity.

A. M. B. Chandima, S. P. Guluwita

Hydraulic Characteristics of Ballast Subjected to Particle Degradation Using Parallel Gradation Technique

Rail tracks are positioned on ballast for the reasons including high load bearing capacity, economy and rapid drainage. It is essential to maintain proper drainage in the ballasted track in order to reduce the pore water pressures during loading that would result in reduced shear strength. The clean and fresh ballast particle assemblage has adequate porosity to facilitate drainage. However, the ballast becomes fouled due to the intrusion of fines either from the subgrade or particle breakage which impairs track drainage as a result of reduced porosity. The degradation (fouling) of ballast can be mainly categorized into two, which are internal particle breakage and subgrade particle intrusion (mud pumping). The aim of this research is to analyse the variation of hydraulic conductivity of ballast subjected to particle degradation by inter particle breakage and fouled with subgrade soil separately. Breakage index is used to state the level of fouling in ballast sample which is fouled with broken down particles and volume based percentage is used to state the level of fouling in ballast fouled with subgrade material in this study. Several constant head hydraulic conductivity tests were conducted with Rowe cell apparatus and parallel gradation technique is adopted to accommodate sufficient amount of ballast sample inside the Rowe cell. The study revealed that, the hydraulic conductivity decreased as the percentage of fouling increased due to the presence of fine particles between the ballast particles.

G. Thanushan, K. Milojan, L. C. Kurukulasuriya

Rapid Conversion of Domestic Organic Waste and Sewerage into Organic Fertiliser to Minimise the Hassle and the Cost of Organic Waste Handling and Sewerage Treatment in Condominiums, Tall and Green Buildings

Household Organic solid waste (HOSW) disposal is a hassle to the house holder and a high cost operation for the local authorities, where it has to be manually collected, transported in garbage trucks and disposed at solid waste dumps located a long distance away. At present, most dump sites have become Garbage Mountains, filled to the brim and at the verge of collapsing and submerging human habitats located in their vicinity, like the “Meethotamulla Municipal Solid Waste Dump Disaster”. In condominiums and tall buildings, where a large number of people live in a small area, the problem is more sever, since a large number of houses are located and HOSW has to be carried manually in lifts or by climbing down large numbers of steps to the round level and dumped into garbage containers, which is collected once in 2–3 days by garbage collectors and disposed at dump sites. In Condominiums, design, construction and operation of sewerage treatment systems, mainly consisting of aerobic and anaerobic microbial digestion has a very high capital cost and a high operational cost. After treatment, the waste water should meet CEA approved parameter values for disposal to the city sewerage system. The paper discusses and provides results of a research project carried out by the author, where HOSW and sewerage were converted into low cost, germ free, odourless, organic fertiliser containing high C, H, O, N, P, K, Ca, Mg by using Delta-D Technology, as a solution to the problems described above. Delta-D Technology is a patented technology developed by the author to rapidly convert all types of organic waste into organic fertiliser.

S. A. S. Perera, M. F. H. M. Aadhil

Investigation of Functionality of Landfill Liner Systems Under Wet Zone Climatic Conditions in Sri Lanka

Engineered land filling is one of the most environmentally friendly methods to dispose municipal solid waste. Bottom liner and top capping are two basic elements of engineered landfill. Bottom liner is expected to prevent contamination of the adjacent environment by leachate. In this study, the performance of two types of clay liners is examined under wet zone climatic conditions in field scale lysimeters. Two 1.5 m diameter and 5 m high lysimeters were constructed to represent an engineered landfill with emphasis to monitor the performance of the liner material placed. In one lysimeter, a 1 m thick liner was placed at maximum dry density using an expansive soil obtained from Moragahakanda area in the central province of Sri Lanka and in the other lysimeter, the liner thickness was reduced to 0.6 m but with the addition of 5% bentonite by weight of the expansive soil. The lysimeters were instrumented to monitor the leachate head generated above the liner and the head developed in the leachate leakage detection pipe. The period of monitoring was extended to include both dry and wet seasons. Based on the monitoring data and using the laboratory measured values performance of the two types of liners were investigated. Geo Slope SEEP/W model was developed to investigate the seepage through both liner types. Based on the actual rainfall values numerical analysis was done to predict the leaked leachate volume through the liner. Those results obtained from numerical analysis were compared with the actual field scale data. The clay liner with 5% bentonite is three times effective in reducing leachate flow rate through the liner when compared with that of control lysimeter. The numerical analysis showed that an increase in liner thickness will reduce the rate of seepage through the liner reaching a limiting value.

H. M. W. A. P. Premarathne, L. C. Kurukulasuriya

Feasibility of Using Mobile Apps in Communication and Dissemination Process of Multi-hazard Early Warning (MHEW) Mechanism in Sri Lankan Context

The alerts given accurately on time via Early Warning mechanisms can save thousands of lives as well as can minimize the level of damage to the Critical Infrastructure to a greater extent. With the rapid occurrence of natural hazards day by day, more emphasis on Disaster Risk Reduction strategies are concerned in order to minimize the disaster-related economic losses and damages. The concept of Multi-Hazard Early Warning emerged with the implementation of Disaster Risk Reduction strategies over the world to work under different global frameworks, mainly with the initiation of the Sendai Framework for Disaster Risk Reduction 2015–2030. Communication and dissemination component of the Multi-Hazard Early Warning mechanism can be considered more significant in terms of reducing the damages and losses over lives and properties. Science and technological applications can be vividly incorporated to enhance the efficiency of delivering Multi-Hazard Early Warning messages from upstream, interface phases towards the downstream community level. With the proper delivery of Early Warning information through technological applications, the efforts on minimizing the damage extent on Critical Infrastructures can be undertaken. This concern is mainly elaborated as one of the seven targets in Sendai Framework for Disaster Risk Reduction 2015–2030. Under this research study, different mobile apps using in different countries are overviewed with the special focus on the comparison of mobile apps that are currently using in Sri Lanka, Maldives and Indonesia. With these concerns, the feasibility of using mobile apps in disaster Early Warning mechanism in Sri Lankan context was examined using a questionnaire survey which was conducted within 10 Grama Niladari divisions. Under this, community responses were collected from 323 responses and these were analyzed using Fuzzy logic approach to identify the decision making scores of the community on level of importance and level of usefulness of the mobile apps.

P. L. A. I. Shehara, C. S. A. Siriwardana, D. Amaratunga, R. Haigh, T. Fonseka

Conceptual Compilation of Activity Criteria During the Post-disaster Stage of a Fire Hazard in Hospitals

The occurrence of fire hazards can cause disastrous consequences in any place and such consequences can be particularly severe in hospitals where a large number of the present population are highly vulnerable in disastrous events. It is also possible that, even after the fire hazard is neutralized, the hospital may remain in a risky position. For example, damages caused due to the electricity framework in the building can cause cascading effects later on by disrupting the power supply of the hospital. Therefore, it is important to seriously consider and undertake the necessary post-disaster activities after a fire. This paper tries to look at all activities necessary to effectively get through the post-disaster stage of a fire-hazard in a hospital so that it can build up its resilience to future fire hazards. This compilation of activities will include post-disaster inspection and cause identification, transfer of patients if necessary and the involvement of insurance agencies. A comprehensive list of activities has been produced separated under five categories of people, buildings and critical infrastructure systems, equipment, hospital material stores, and post-fire administrative and managerial work. Here, it is also discussed which of these activities should be applied to a scenario depending on the impact level of the fire hazard.

W. D. M. Kularatne, H. H. H. Hasalanka, C. S. A. Siriwardana, W. K. D. Rathnayake, H. T. V. Fonseka

Development of a Hospital Safety Assessment for Tsunami in the Sri Lankan Context

In the context of disasters, hospitals act as a safe place for both patients, victims and several other stakeholders. The 2004 Indian Ocean Tsunami could be identified as one of the most disastrous events which significantly impacted the coastal region in Sri Lanka. Many infrastructure and buildings were affected and destroyed due to the extremity of the event including hospitals located in the coastal line. Hence, it is necessary to assess the level of safety of existing hospitals in the coastal region in the event of a tsunami. Therefore, a hospital safety assessment tool should be developed for Tsunami under the Sri Lankan context. Since, the structural condition of buildings, functional and operational aspects, as well as the emergency management aspects, are vital to ensure the safety of hospitals under tsunami, all of these were included in the assessment tool. The most cost-effective and efficient method to obtain the level of structural safety of hospitals is the Rapid Visual Screening (RVS) method. It is because the safety level could be obtained through a sidewalk survey. In other words, the level of safety could be obtained with the RVS method through visual observations with the naked eye, without using any equipment. Also, the functional, operational and emergency management aspects could also be easily assessed through observations, reviews of documentation and structured interviews. As the developed assessment tool is expected to be used to assess the level of safety of existing hospitals, the Rapid Visual Screening (RVS) method along with the reviews of documentation and the methods of structured interviews were adapted to the assessment tool. As the initial step of developing the assessment tool, an attribute list was developed considering the available literature. For RVS structural safety assessments, the Papathoma Tsunami Vulnerability Assessment (PTVA) model and FEMA guidelines are widely used. Among these two guidelines, the PTVA model is specifically developed for tsunami while FEMA guidelines are developed for cyclones, seismic activities, floods, etc. Furthermore, the Hospital Safety Index (HSI) guide published by the World Health Organization (WHO) includes a comprehensive assessment tool related to functional, operational and emergency management categories. The developed attribute list was used to assess selected hospitals in the southern coast of Sri Lanka, in order to obtain the applicability of the developed attributes. This paper discusses the development procedure of the initial attribute list to assess the level of safety of a hospital in Sri Lanka under a Tsunami. After that, a comprehensive assessment tool could be developed through the feedback obtained through the study along with the experts’ opinions.

H. H. H. Hasalanka, C. S. A. Siriwardana, W. D. M. Kularatne

Effect of Corner Strength Enhancement on Shear Behaviour of Stainless Steel Lipped Channel Sections

During the cold-forming process of manufacturing, stainless steel sheets undergo plastic deformations, in particularly around corner regions of press braked sections. These plastic deformations lead to significant changes in material properties of stainless steel compared to its flat sheet properties. Consequently, yield strength and ultimate strength increments can be envisaged and this process is termed as cold working. Stainless steel exhibits significant level of strain hardening under plastic deformations. This is the main reason for these strength enhancements. In the structural design process of stainless steel sections, these strength increments are required to be considered to harness the benefits arising from it. Therefore, previous research proposed predictive models for these strength enhancements. In this context, the effect of corner strength enhancement on press-braked stainless steel lipped channel sections under shear was examined in this paper. 120 finite element models were developed. Different corner radii and section thicknesses were taken into account. Results highlighted that the effect of cold working on the shear capacity of stainless steel lipped channel sections is more significant in compact sections compared to slender sections where up to 9% increment was observed. Further analysis was conducted using 40 finite element models to highlight the inelastic reserve capacity available in compact stainless steel lipped channel sections in shear. From the results, it was concluded that when web slenderness is less than 0.25 more than 40% shear capacity increment can be achieved due to strain-hardening of stainless steel.

D. M. M. P. Dissanayake, K. Poologanathan, S. Gunalan, K. D. Tsavdaridis, N. Degtyareva

Shear Behaviour of Cold-Formed Stainless Steel Lipped Channels with Reduced Support Restraints

Lipped channel beams are commonly used in buildings for load-bearing components such as floor joists and roof purlins. The typical practice is to use one-sided web side plates (WSPs) to attach beams from their webs to the supports at the connections, through bolts. In such realistic conditions, it is not practical to use WSPs over the full height of the webs, thus only a part of the web height is restrained at the supports. This controls the mobilising of diagonal tension field in the web and also provides less restraint to the lateral movement of the web. Therefore, realistic support conditions affect the shear capacity due to the lack of restraint of the web at the supports. On the other hand, the current shear design rules are based on ideal support conditions which do not represent the true scenario. Therefore, it is critical to investigate the effect of reduced support restraints on the shear capacity since it has been given less attention in the literature. This paper presents the effect of reduced support restraints on the shear capacity of stainless steel lipped channel beams. Finite element models were developed to study the effect with regard to various influential parameters. From the finite element results, it was found that the shorter the WSP—the higher the shear capacity reduction, where about 50% shear capacity reduction was observed for 60% reduction in WSP height. Furthermore, it was concluded that compact sections exhibit more significant capacity reduction than slender sections when reducing the WSP height. Therefore, a reduction factor was introduced to the current direct strength method shear design rules considering the effect of reduced support restraints on the shear capacity.

D. M. M. P. Dissanayake, K. Poologanathan, S. Gunalan, K. D. Tsavdaridis, K. S. Wanniarachchi

Influence of Type of Interfaces on Railway Ballast Behavior

Railroads are one of the most popular modes of transportation in many countries including Sri Lanka. However, rapidly growing populations and increasing congestion in road transport have created severe challenges to the sustainability of rail transport infrastructure, which in turn elevate the demand for increased speed and higher capacity trains. Due to the increase of speed and load, excessive lateral stresses are induced in rail track foundations leads to lateral instability of the track. Ballast layer underneath and around the sleeper play significant role in resisting lateral movement and give stability to track structures. In addition to the ballast shear resistance, there are various interfaces in rail track such as ballast-sleeper (timber or concrete), ballast-resilient pads (under sleeper pads-USP or under ballast mats-UBM), and ballast-subgrade (or subballast) significantly influencing the overall shear behavior. It is important to understand the shear behavior of these interfaces. Therefore, this study is to evaluate the shear behavior under static loading condition of some of the commonly used interfaces found in ballasted rail track using large-scale direct shear apparatus considering full size ballast particles collected from nearby rail ballast quarry. The large-scale direct shear test has been carried out for fresh ballast and three different interfaces: (i) ballast–concrete sleeper, (ii) ballast–timber sleeper and (iii) ballast–USP under three different normal stress conditions (30, 60 and 90 kPa). Shear strength parameters of interfaces are evaluated and compared with that of the fresh ballast shear parameter. In addition to that, ballast degradation behaviour is also analyzed using the Ballast Breakage Index (BBI) method.

S. K. Navaratnarajah, K. R. C. M. Gunawardhana, M. A. S. P. Gunawardhana

Effect of Loading Sequence in Fatigue Life Prediction of a 130 Years Old Railway Bridge

The Miner’s rule is the simplest and the most commonly used fatigue life estimation technique for railway bridges [1]. One of its salient features is that life calculation is simpler and reliable when the detailed loading history is unknown. Further, it has been recognized for fatigue damage estimation in various codes of practices. However, in the case of existing railway bridges where the detailed loading history is known, Miner’s rule might provide incorrect results because it does not not properly take account the loading sequence effect. In the light of this fundamental deficiency, a new damage indicator has been proposed to capture the load sequence effect more precisely by Mesmacque et al. (Int J Fatigue 27:461–467 [2]). The new damage indicator has successfully been applied by Siriwardane et al. in 2008 for fatigue damage estimation of a major bridge in Sri Lanka. From 2012 onwards, Sri Lankan Railways has introduced heavier class of locomotives and some of these new loco’s have more than 40% heavier engine weights than previously used locomotives. The major objective of this study is to estimate the remaining fatigue life of above railway bridge using the sequential law under increased live loads. The bridge is one of the longest railway bridges in Sri Lanka, constructed in 1885, which is still in operation. A Finite Element model of the bridge was developed using SAP2000 V.14 general purpose software package and the fatigue damage estimation is performed by using a Mathlab code. The obtained fatigue lives are compared with commonly used Miner’s estimations. The obtained results verify the effectiveness of the proposed model over commonly used Miner’s rule for life prediction of steel bridges. Hence it could be concluded that it is advisable to apply the sequential law for assessment of remaining fatigue lives of riveted railway bridges, where the detailed stress histories are known. The results further strengthen the idea that necessity of sustainable asset management of civil infrastructures.

P. A. K. Karunananda, H. K. C. U. Herath, W. S. Madusanka, W. M. A. D. Wijethunge

Comparison of Rheology Measurement Techniques Used in 3D Concrete Printing Applications

3D Concrete Printing (3DCP) is a novel and emerging construction technique to build using digital technologies and additive manufacturing concepts. Some main advantages of 3DCP are reduced formwork wastage, the capability of constructing complex geometric shapes, higher precision, shorter construction time and increased safety. In the particular method, the structure is built layer by layer by extruding the material through a nozzle. Initially, the material should be pumped and extruded with considerable fluidity and workability. Immediately after the extrusion, the extruded layers should have enough strength and stiffness to retain the desired shape. Therefore, controlling the rheology of the material is of high importance in 3DCP. Due to the higher stiffness, and higher time and rate-dependent material behavior (thixotropic behavior) compared to the conventional concrete, conventional rheology measurement techniques have many limitations when used for 3DCP material. Therefore, non-conventional (direct shear test, orifice extrusion, vane shear test), as well as conventional rheology measurement techniques (rotational rheometer and slump test), were conducted to compare the results and to characterize the rheological parameters. The rheological parameters (i.e. yield stress, viscosity, and thixotropic build rate) of concrete were measured for three different mixes. The achieved values were compared to decide the most suitable and reliable test method. The pros and cons of each test method also were discussed. The achieved yield stress values are different according to the test method used. However, a similar trend can be seen in all the testing methods. Rotational rheometer gives the lowest yield stress values, while an orifice extrusion test gives the highest yield stress values. Finally, it can be predicted that the extrusion-based testing methods such as orifice extrusion technique used in the current study give reliable results on yield stress and viscosity measurements due to the similarities between the measurement technique and the actual 3D printing extrusion process.

Roshan Jayathilakage, Jay Sanjayan, Pathmanathan Rajeev

A Feasibility Study for Natural Disaster Simulations Using a Fully Explicit SPH Method in a GPU Environment

Mesh-free particle methods are increasingly being used instead of grid based numerical methods in many engineering applications, including free-surface fluid flows. Smoothed Particle Hydrodynamics (SPH) method is one such meshless, Lagrangian particle method utilized for modeling large deformations or flows with free surfaces. In SPH, the problem domain is discretized into particles without any connectivity and physical quantities of the flow are obtained by tracing the motion of particles. SPH was originally developed for compressible flow and has later been improved to satisfy the incompressible condition by various authors. In typical incompressible smoothed particle hydrodynamics (ISPH) formulations, a semi-implicit integration scheme is applied to particle discretized equations to solve incompressible flow problems. This requires solving linear equations, which takes up a lot of device memory, thus limiting the possibility of carrying out large scale problems. This study explains the application of a fully-explicit time integration scheme for fluid simulations using the ISPH method. In addition, we used a GPU environment for the computer simulations through an authorial program written in CUDA Fortran. Thus, the purposes were to avoid the need of solving linear equations, therefore reducing memory usage and to utilize the parallel processing power of GPU to accelerate the code. On the other hand, GPU is more widely available compared to supercomputer CPUs, which is the generally used environment for ISPH calculations. Dam-break simulations and validation tests were conducted to validate the proposed SPH method. With the proposed method and computational environment, the calculation speed was increased and memory usage was decreased significantly and large fluid simulations could be carried out. Thus, the proposed method and improvements could pave way in simulating large-scale problems, such as tsunami run-up analyses and other natural disaster simulations.

H. T. Senadheera, M. Asai, D. S. Morikawa

Surfactant/Citrate Assisted Synthesis of Calcium Carbonate Nanostructures from Natural Calcite

Synthesis of nanostructures from naturally available and easily accessible natural minerals is a growing area of research. It would be beneficial if nanotechnology is exploited for the value addition for inadequately utilized the aforementioned minerals. Calcium carbonate nanostructures can be employed in industrial products to improve their mechanical and other functional properties. In this study, citrate ion template-based method was employed for the synthesis of precipitated calcium carbonate nanostructures from naturally occurring calcite with different morphologies and sizes. For characterization of synthesized materials, X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Thermal Gravimetric Analysis, and Scanning Electron Microscopic analysis were used. “Grain” like structure was observed from citrate template-based method while nanoparticles synthesized using surfactant-citrate method exhibited a surface morphology which is spherical in nature. The particle size of 70–80 nm was observed from nanoparticles using surfactant/citrate method and citrate template-based synthesized nanoparticles exhibited dimensions of 90 nm × 300 nm. Owing to the simplicity and cost-effectiveness, this novel method of synthesizing calcium carbonate nanoparticles would be industrial feasible approach.

M. R. Abeywardena, D. C. N. A. Wickramarathne, B. D. A. S. Fernando, D. G. G. P. Karunarathne, H. M. T. G. A. Pitawala, R. M. G. Rajapakse, A. Manipura, M. M. M. G. P. G. Mantilaka

Fully-Modular Buildings Through a Proposed Inter-module Connection

Modular buildings are built using factory manufactured building units or modules that are transported and assembled on-site. Among the many different types used, modules of volumetric form analogous to intermodal freight containers have the greatest potential to achieve complete building systems or fully-modular building systems where on-site work could be reduced to foundation, module assembly and the finishing of module-to-module interfaces as required. However, despite the many reported benefits, volumetric module use has some technical, logistical and regulatory issues that have constrained its widespread application. Two of such issues that have been widely reported are the lack of efficient structural systems for lateral load transfer and the lack of high-performance inter-module connections that can not only meet structural demands but can also fulfil certain constructional and manufacturing needs as well. Therefore, this paper focuses specifically on the latter of the two identified issues and briefly summarises the work conducted into its resolution.

S. Srisangeerthanan, M. J. Hashemi, P. Rajeev, E. Gad, S. Fernando

Determining Roundabout Capacity by Modifying HCM Model Under Mixed Traffic Conditions

Roundabouts are commonly implemented as transportation infrastructure facilities due to their improved performance. Capacity is a key performance measure of a roundabout which is considered at its design stage. Highway Capacity Manual (HCM) 2010 provides an exponential regression model for determining capacity at entry for a roundabout. However its applicability in heterogeneous traffic conditions has not yet been thoroughly researched. In Sri Lanka the island nation in the Indian Ocean, the percentage of contribution to the vehicle mix by motorcycles and three-wheelers are 45–55%. Thus, in this study HCM 2010 roundabout capacity model was modified to determine the capacity of a selected four legged roundabout in Kandy, Sri Lanka. Data acquisition was carried out by a turning movement count survey and video recording. Circulatory traffic volume, composition of each vehicle class, critical gap and follow-up headway were determined. A method incorporating the mixed traffic conditions was adopted to determine critical gap value. Stream equivalent follow up headway of 2.97 s and critical gap value of 5.07 s were used to determine the entry capacity. The graph plotted for variation between circulatory flow and entry flow at the roundabout was in negative exponential behaviour. The graph showed that entry capacity reduced exponentially when the circulatory flow increased. The study was further extended to determine adjustment factors for capacity estimation from the HCM 2010 roundabout capacity model directly. The results of this study could be useful in sustainable design of roundabouts in countries that experience mixed traffic conditions like Sri Lanka.

M. A. K. Sandaruwan, H. K. D. T. Karunarathne, W. M. V. S. K. Wickramasinghe

Capacity Analysis for Urban Roundabouts in Sri Lanka Using Modified  SIDRA Model

Traffic performance of an intersection can be more effectively controlled by roundabouts than other methods due to increased safety and efficiency. Vehicle flows merge and diverge at small angles with low speeds in one circulatory direction within the roundabout. Designing a roundabout requires thorough analysis of its capacity and other performance parameters. There are many methods to estimate the capacity of roundabout entry. However these methods are developed in countries with homogeneous traffic conditions which consist of higher percentage of passenger cars. Traffic flows in Sri Lanka consists of 45–55% of light vehicles such as motor bikes and three wheelers. Therefore, most available roundabout capacity estimation methods cannot be directly applied to the traffic condition in Sri Lanka. An adjustment should be done to the mixed traffic condition before applying the existing estimation methods. This research aims to introduce an adjustment method to estimate the capacity of urban roundabouts in Sri Lanka by modifying the SIDRA roundabout analysis method. Statistical analyses were done to identify the significance of the adjustment methods. The results show that the existing SIDRA model can be used when the traffic flow is adjusted using passenger car equivalency factors. It can be concluded that the adjustment method gives more sustainable estimations to the roundabout entry capacity for local traffic flow conditions.

H. K. D. T. Karunarathne, M. A. K. Sandaruwan, U. K. A. H. Madushani, W. M. V. S. K. Wickramasinghe

Investigation of the Institutions Formed and Empowered from Disaster Risk Governance Policies: Case Studies from Sri Lanka, Myanmar and Maldives

Regardless of the country, communities are highly vulnerable and exposed to disasters induced by natural hazards. There is a number of disaster risk management mechanisms in place to mitigate and address disasters. A question unanswered regarding the disaster risk management mechanisms is why the damage and destruction due to disasters are not getting decreased and why are the same errors getting repeated. Hence, it is required to evaluate the effectiveness of these disaster risk management mechanisms to better tackle disasters. When understanding the disaster risk management mechanisms there are policies, which govern the mechanisms, and there are institutions, which operate, empowered and defined from these policies. Institutions that govern, plan, address and response to disasters are different and have different mechanisms of work. Networking, coordination, and dependencies of the institutions are a critical factor in disaster risk management. This research paper analyses the empowerment of institutions and identifies the placement of institutions in risk management mechanisms comparatively. The research study is based on case studies from Sri Lanka, Myanmar, and the Maldives. A number of community visits and institutional visits were conducted in three countries for the data collection of the research work. It was observed that in the above-mentioned countries, different approaches, techniques, and processes are used for disaster risk management. Hence, initially, this research study attempts to holistically understand the overall scenario of policies in place for disaster risk governance. As the next step, all the institutions were mapped and summarized for analysing. The outputs from the research work can be used to understand the interdependencies of an institution in the disaster management mechanisms and to evaluate the involvement of each institution in disaster risk management.

W. K. D. Rathnayake, C. S. A. Siriwardana, C. S. Bandara, P. B. R. Dissanayake

Piled Raft Foundation System for Tall Buildings

Design of a safe and economical foundation system is an important task in tall build-ing design. Deep foundations such as piled foundations are generally adopted to transfer heavy loads from superstructure to the bearing stratum. Providing adequate geotechnical capacity and limiting the deferential settlement are two important design considerations in the design of piled foundations. The foundation design becomes economical when both the criteria of bearing capacity and settlement are satisfied in an optimum way. A piled raft foundation is an advanced concept in which the total load coming from the superstructure is partly shared by the raft through bearing from soil and the remaining load is shared by piles through skin friction and end bearing. Consequently, piled raft system is generally adopted when pile foundations for tall buildings become uneconomical or unsatisfactory. Due to the three dimensional nature of the load transfer, piled raft foundations are regarded as very complex systems involving many interaction factors such as pile-to-raft, raft-to-soil, and pile-to-soil. This paper intended to present a detailed discussion on the analysis of piled raft system addressing available analytical methods to analysis piled raft system. Considering of deferent factors influencing the pile raft behaviour are summarized in this paper. A detailed numerical analysis approach for the analysis of piled raft foundation is discussed. Further, a case study investigating the performance of piled raft system for an eighty-one storied tall building is presented.

B. G. S. T. Gamage, B. Kiriparan, B. Waduge, W. J. B. S. Fenrnado, P. Mendis

Stakeholder Preference for Ongoing Green Urban Planning in Kandy

Urban planning has become a mind stimulating concept in the twenty-first century which has been successfully adapted by many countries in the world in order to achieve a sustainable urban development. Stakeholders as the ultimate beneficiaries, plays a vital role in urban development platform whose opinions must be critically considered in the decision making process of urban planning. This research attempts to question and assess the preference of three stakeholder groups regarding the planning interventions that have been applied recently in the Kandy urban development platform. Its objective is to contribute insights to the planning and design of urban greening in Kandy in order to support user needs and preferences. The study is conducted through mixed methods via a visual preference survey and a semi-structured questionnaire survey. Samples were selected by judgmental sampling method including professionals, permanent residents and daily travelers within the Kandy Municipal Council area. This study reveals that the three stakeholder groups have different preferences towards the ongoing urban planning interventions based on their daily interactions with the city. In a nutshell, it can be stated that the stakeholder preference is well inclined towards manageable urban green spaces. They prefer the ongoing projects implemented beneath strategic cities development programme where the green features are incorporated and sometimes their preference pervades over strategic interventions and embrace the existing natural. Stakeholders emphasize the drastic need of green infrastructure planning into Kandy as a futuristic strategy in order to bridge the gap between compact urban constructions and natural ecosystems. Hence, it’s essentially important to promote a social discourse on best green planning practices raising awareness and academic stimuli. Moreover, the research evidences can be utilized to indicate the potential strengths and weaknesses of ongoing planning endeavors and broader researches must be conducted to execute further visually preferred plans in Kandy.

E. G. I. Sevwandi

Prediction of Across Wind Response of Tall Buildings: An Overview

Wind induced lateral loading is one of the vital factors governing the design of tall buildings. Along wind, across wind and torsional responses are three important considerations in wind design of tall buildings. A well-established gust factor approach is adopted in most of the wind design codes to predict the dynamic response of tall buildings in the along wind direction. Along wind predictions using this approach is found to be with reasonable accuracy when the wind flow is not significantly affected by neighbouring buildings. However, the applicability of most of the wind design codes are restricted to regular shaped structures with limitation on height or natural frequency. Dynamic motion of tall and slender structures perpendicular to the direction of the wind is known as across wind excitation. This phenomenon can be resulted from three mechanisms and their higher time derivatives such as vortex shedding, incident turbulence mechanism and higher derivatives of crosswind displacement (i.e., galloping, flutter and lock-in). Due to the complex nature of the wind, characteristics of vortices and its interaction with the structure, significant limitations are found among the provisions set out in different international standards for the prediction of across wind responses. Though most of the existing codes are capable of predicting the along wind loading to reasonable accuracy, only a few international standards provide provisions for across wind effects. Unlike the along wind responses significant discrepancies are found among the across wind responses estimated by different standards. This paper presents an overview of capabilities and limitations of design provisions available in seven international codes/standards such as BS 6399-2:1997, BS EN 1991-1-4:2005, AS/NZS1170.2:2011, AIJ: 2004, CNS: 2012, ASCE 7-10 and NBCC: 2005 for the prediction of across wind responses. Comparisons of predicted across wind induced response for different building configurations (range of plan aspect ratio form 1–2, height aspect ratio from 4 to 8 and height from 120 to 240 m) are used to explain the influence of methods adopted in each of those wind codes.

B. Kiriparan, J. A. S. C. Jayasinghe, U. I. Dissanayake

Enablers for Effective Multi-hazard Early Warning System: A Literature Review

The intensity and frequency of natural hazards have increased unprecedentedly, resulting in devastating impacts on lives and economies. The present challenge for practitioners and policymakers is to reduce such impacts and related risks with innovative measures. A multi-hazard early warning system has been recognized as a crucial element in most disaster risk reduction measures. However, recent hazard incidents revealed that existing early warning systems are not completely able to save lives and reduce economic losses due to many reasons. Hence, this paper is conducted to provide a comprehensive understanding of the enablers to be considered when developing a fully comprehensive multi-hazard early warning system. Further, the study presents the benefits of establishing an effective multi-hazard early warning over single early warning systems. The paper is based on a narrative review applying a systematic basis for selecting research papers for the study. According to study results, three aspects to be considered when developing and operating an effective multi-hazard early warning system. Policy, legislative and institutional arrangements; social and cultural considerations and technological and scientific arrangements are the three categories. Policy, legislative and institutional arrangements contain governance, political recognition, mainstreaming early warning into development planning, stakeholder partnerships, periodic feedback, empowerment of local authorities and provision of resources/infrastructure. Social and cultural consideration includes training and capacity building, awareness and education, planning and preparedness, community engagement and empowerment and consideration of gender perspective and cultural diversity. Finally, integration of technological and scientific knowledge, risk information, hazard warning dissemination and communication, and monitoring and forecasting are the technological and scientific arrangements to be assured for an effective multi-hazard early warning for disaster risk reduction and enhancing resilience.

K. Hemachandra, R. Haigh, D. Amaratunga

Deterioration Modelling of Timber Utility Poles

Timber utility poles are extensively used in power distribution and telecommunication sectors to support the overhead cables and other attachments. These utility poles are designed to have sufficient inherent capacity to withstand the imposed actions. However, timber poles deteriorate with time losing the strength and toughness mainly due to weathering, decay and termite attacks. Therefore, pole failures occur when the imposed stresses on the pole exceed the remaining strength of the pole. It is essential to avoid pole failures which will have severe safety concerns and significant economic impacts. This paper presents a brief review of the currently available timber deterioration models and proposes a framework for evaluating the residual strength of the in-service timber utility poles. The developed framework permits the asset managers to evaluate the structural reliability of these assets and to determine the optimum pole replacement rates. The residual strength of an in-service pole is directly related to the remaining section modulus of the pole at its critical section which is the ground line region of the pole. Hence, this paper presents the evaluation of the remaining section modulus for sectioned pole specimens which were condemned from service due to pole replacements. Further, the variation of section modulus with the service life is illustrated for the analysed Australian pole specimens and compared with the predictions of the current deterioration models.

S. Bandara, P. Rajeev, E. Gad

Effect of Polypropylene Fibres on the Workability Parameters of Extrudable Cementitious Materials

Additive manufacturing in construction industry has been introduced as an aspiration for a more sustainable built environment and currently evolving with high demand amongst researches. This study is an investigation of the influence of polypropylene (PP) fibre addition on the workability parameters of a new extrudable concrete mixture. As the quality of final printed structure prominently depends on the fresh state properties of concrete, this investigation mainly focused on the rheological properties such as workability (flow), setting time, extrudability and buildability. These parameters were systematically investigated through a small scale experimental process with time after mixing. The selected control mix with Ground granulated blast furnace slag (GGBS) and Silica Fume (SF) was used in this analysis. The Control cementitious specimens without fibre inclusion and with fibre addition in different volume fraction of binder, ranging from 0.5 to 3% were printed. The results showed that the fibre addition of 0, 0.5 and 1.0% have the better flowability and extrudability compared to 1.5, 2 and 3%. Also, reduction in the print quality was assessed visually with increasing fibre percentage. However, results indicated that the initial setting time is comparatively low for those mixes with higher fibre inclusion which is required for better bond strength between layers. Moreover, higher fibre content caused better buildability and shape retention in the extruded samples.

T. Suntharalingam, B. Nagaratnam, K. Poologanathan, P. Hackney, J. Ramli

Synthesis of Carbon and Silica Nanospheres for Removal of Heavy Metals in Wastewater

Treatment of heavy metals containing industrial effluent becomes quite necessary before being discharged to the environment. In this study, potential of carbon nanospheres (CS) and silica nanospheres (SS) for the adsorption of heavy metals were tested. SS were synthesized by the Stӧber process and CS were synthesized by a slightly modified Stӧber process. Products obtained were tested with Scanning Electron Microscope to identify their spherical shape. N2 adsorption-desorption analysis was conducted to measure the specific surface area and porosity. SS showed higher total pore volume compared to that of CS and CS showed higher specific surface area compared to SS. Adsorption capacities of both particles were tested for lead ions (Pb2+) through equilibrium and kinetic studies. SS showed a better adsorption capacity than CS. Results show no substantial difference. So, both can be used as effective adsorbents to remove heavy metals in wastewater. This study can be extended to obtain the best material which has a greater adsorption capacity by adjusting synthesis conditions.

H. M. R. S. Herath, W. M. M. C. Welagedara, C. A. Gunathilake

Integration of the Concept of Disaster Resilience for Sustainable Construction—An Analysis on the Competency Requirements of the Built Environment Professionals

Sustainable construction involves a commitment to: Economic sustainability, Environmental sustainability and Social sustainability. However, the notion of ‘resilience’ has not been mainly integrated to the sustainable construction. Within this context, researchers have emphasised the need to bring these two notions ‘sustainability’ and ‘resilience’ into one framework as both these notions are interrelated. However, in order to integrate disaster resilience to the sustainability agenda, it is extremely important to identify the competency requirements of the built environment professionals. As a part of a key research project entitled CADRE, an analytical framework was developed to identify various built environment professionals, different resilience aspects and stages of the construction project cycle. Accordingly, based on this analytical framework, an extensive literature review was conducted to identify the competency requirements of the built environment professionals under different resilience aspects in the construction stage of the project cycle. Findings reveal, that the built environment professionals should have a variety of competencies to enhance resilience in the built environment projects and through that contribute to integrate the notion of resilience to the sustainability agenda.

N. Dias, D. Amaratunga, R. Haigh, C. Malalgoda, S. Nissanka

Review on Geosynthetic Inclusions for the Enhancement of Ballasted Rail Tracks

Currently, there is an increasing demand for rail transport from a growing and urbanizing population worldwide as it is a resource-efficient transport system. Moreover, its popularity among people is due to safety, reliability and economic profit. The rail track system consists of rails, fastening systems, sleepers, ballast, sub-ballast and subgrade. Ballast is a highly angular coarse granular material which is the major load-bearing component as it transmits the stresses exerted by moving trains from sleepers to the subballast and subgrade at a reduced level. Ballast degradation is a major problem caused by the high dynamic and cyclic loads from faster and heavier trains as well as the impact loads due to wheel and rail irregularities and tracks at stiffness transition zones. It affects the track longevity together with the track geometry thereby a necessity of regular monitoring and maintenance. Ballast fouling is accompanied by ballast degradation as the broken ballast particles intrude into the voids of the ballast layer and obstruct the drainage. The popular method to reduce the excessive ballast deformation and degradation is the inclusion of geosynthetics such as geogrids, geotextiles, geocomposites, and geocells to the track foundation. This paper provides an extensive review of past studies on geosynthetics to reinforce the track foundation. In conclusion, this review presents the limitations of existing studies and provides recommendations for further studies.

S. Venuja, S. K. Navaratnarajah, C. S. Bandara, J. A. S. C. Jayasinghe

Finite Element Modelling of Wall Panels Under Standard and Hydrocarbon Fire Conditions

Fire is one of the severe conditions in which structures may be exposed during their life span. When considering the structural elements, wall panels play a vital role during a fire scenario, since the spreading of the fire could be either controlled or accelerated due to the type of the wall partition. Standard fire tests are generally used to evaluate the fire performance of structural elements. However, the fire tests are expensive and time consuming to carry out. Therefore, numerical methods have been developed to evaluate the fire performance of these structural elements. In this study ABAQUS, finite element software was used to model the fire performance of lightweight foamed concrete and normal weight concrete wall panels. Experimental results of the previous studies were used to validate the models. Parametric studies were conducted using the developed models to evaluate the fire performance of two different types of wall panels under standard and hydrocarbon fire conditions. Lightweight foamed concrete wall panels exhibited better fire performance compared with the normal weight concrete wall panels. Three to five times of fire performance enhancement under insulation criteria could be obtained for wall panels of different thicknesses, by replacing normal weight concrete wall panels with lightweight foam concrete wall panels.

I. R. Upasiri, K. M. C. Konthesingha, K. Poologanathan, S. M. A. Nanayakkara, B. Nagaratnam

Low Fidelity Numerical Models for Evaluation of Subgrade Reaction: A Review

In soil-structure interaction problems, both the superstructure and the subgrade must be analyzed together in order to determine the overall behaviour accurately. In geotechnical engineering problems, software with advanced soil models is often used to represent the complex soil characteristics. However, merging such a model with the superstructure modelled in detail will demand unrealistic large computational cost. In this context, adopting low fidelity numerical models to represent soil-structure interaction is more effective. These models are both relatively easy to implement using commercially available software as well as represent the soil characteristics sufficiently correct. Two basic classical approaches namely the Mechanical approach and Continuum approach are identified in literature when it comes to modelling of subgrade. Later, using the features of both approaches, hybrid models have been developed. Numerous modified subgrade models that use mechanical, continuum and hybrid approaches have been proposed in the literature. This paper investigates and describes the possible soil-structure interaction models available in the literature and presents a classification based on the theory behind their evolution. Strengths and limitations of various types of models are discussed in brief in order to choose the most suitable model for a particular problem.

R. M. D. L. Rathnayake, S. K. Navaratnarajah, C. S. Bandara, J. A. S. C. Jayasinghe

Assessment of Groundwater Quality for Drinking Water from Deep Confined Aquifer in Wanathawilluwa

Potable water draws attention of human being due to scarcity of clean water. Contamination of surface, subsurface and groundwater has thus become a serious problem in nationwide. Hence, the assessment of water quality is utmost important to preserve and restore the surface, subsurface and deep-water sources. The main intent of this paper is to present of the groundwater quality status for future planning and management of Wanathawilluwa aquifer in Puttalam district. The assessment of the water quality was carried out in the different locations at Wanathawilluwa. Physiochemical analysis was carried out for surface, subsurface and deep aquifer water samples to provide a single number for Water Quality Index (WQI) that expresses the overall water quality of corresponding water at certain location. WQI was calculated using the weighted arithmetic index based on several water quality parameters such as pH, Total Dissolved Solids, Phosphate, Nitrate, Turbidity, Electrical Conductivity, Dissolved Oxygen and Chemical Oxygen Demand. By representing the whole Wanathawilluwa aquifer, 21 deep and subsurface water samples from different locations were tested and results were compared with stipulated Sri Lanka Standards for potable water. The estimated WQI of Wanathawilluwa aquifer reveals that the overall water quality class is ‘good’ and water is acceptable for domestic use.

A. C. Galhenage, E. G. S. S. Kumari, A. M. L. U. Kumara, T. W. L. R. Thalgaspitiya, V. Edirisinghe, M. Vithanage, B. C. L. Athapattu

Finite Element Modeling and Simulation of Rubber Based Products: Application to Solid Resilient Tire

This paper explores the procedure of selecting the best-fitted hyper-elastic material model to describe the mechanical behavior of filled vulcanized rubber-based products, by using nonlinear 3D numerical simulation. Constitutive relationships of these hyper-elastic material models are represented by the strain-energy density functions with the form of polynomial equations. These models utilize to capture the non-linear elasticity and incompressible behavior of elastomers, such as rubber-like materials. In this study, the curve fitting approach and three statistical indexes (MAPE, MAD, and MSD) are proposed to find the best fit hyper-elastic material model and coefficients for a given set of test data of a filled vulcanized rubber sample. Moreover, it highlights the contradictories of each material model by considering the available test data. A three-layered solid resilient tire is used as the numerical example for this study. In this numerical study, the minimum values of the three statistical indexes and coefficients which are obtained from the best-fitted material model with the given experimental data are conformed. The results show that the Yeoh model has a good agreement with the stress-strain curve, which obtained from the experimental data. Further, a static analysis is conducted on the target industrial solid tire, by introducing the selected material model and reasonable displacement and stress results are obtained.

N. M. L. W. Arachchi, C. D. Abegunasekara, W. A. A. S. Premarathna, J. A. S. C. Jayasinghe, C. S. Bandara, R. R. M. S. K. Ranathunga

A Review on Thermo-mechanical Behaviour of CFRP-Concrete Composites at Elevated Temperature and Available Insulation Systems

The use of Carbon Fibre Reinforced Polymer (CFRP) composites have become a prominent solution for retrofitting the concrete structures. Though CFRP composites have superior mechanical properties, resistance of CFRP/Concrete composites to fire remains unsolved. The degradation of the epoxy resin at elevated temperature makes the FRP composites weaker due to the low glass transition temperature of epoxy resin. A review on CFRP-concrete composites at elevated temperature and available insulation systems are presented in this paper. The paper summarises the results obtained from experimental and numerical studies on the fire performance of CFRP-concrete composites. Hence, it was concluded that by providing appropriate insulation system, the CFRP-concrete members can be protected from fire. However, there are several drawbacks with available insulation systems, such as high cost, addition of dead load, and less aesthetic appearance which are also discussed in this paper.

A. Selvaratnam, J. C. P. H. Gamage

Utilization of Textile Waste in Development of Interlocking Paving Blocks for Foot Paths

Unrecyclable fabric waste generates a major environmental problem in Sri Lankan textile industry. Embedding polyester spandex fabric waste into cement matrix for manufacturing of paving blocks was investigated in this study. In the initial stage of investigation, effect of shredded form of polyester spandex pieces in cement paste was investigated to find the optimum fabric content which can incorporate into cement paste-fabric mix. Admixtures were used to prevent segregation of fabric pieces from cement paste and to improve the workability of mixture. There were improvements of compressive strength of cement paste with shredded fabric and the optimum strength was achieved at 26% of fabric content by volume. Interlocking paving blocks were cast with the use of manufactured sand, shredded form of fabric and cement which were tested for compressive strength, splitting tensile strength and water permeability. Two distinct mix proportions yielded high compressive strength and splitting tensile strength, which were 17.42 MPa and 3.64 MPa, respectively. Hence, depending on the strength requirement, the user can select the suitable mix proportion for a particular application. Failure pattern of fabric incorporated paving blocks gives an indication on its energy absorption capability which can provides better foot comfort by using these paving blocks in foot paths, jogging paths and surfaces for sports areas. Water permeability of fabric embedded paving blocks are 100 times greater than that of conventional cement paving blocks which helps to reduce surface runoff during a heavy rain.

G. K. B. M. Gannoruwa, S. M. A. Nanayakkara, S. S. K. Muthurathna

Fires and Building Safety

Fires are widespread during the recent past and wildland fires and building fires have been reported. A building is computer modeled using Zone Modeling concept to study the temperature and smoke distribution of a one-story building due to a fire based on conservation of mass and energy. The results documented have smoke distribution as well as oxygen and carbon dioxide levels at different targets of the building and correlate to the levels of human exposure to the products of combustion.

R. Purasinghe, J. Chavez De Rosas, G. Mejia, M. Thomas, X. Chen

Ultra-Low Cycle Fatigue Failure Analysis of Steel Concentrically Braced Frames Using Non-Linear Fiber Beam Column Elements

Earthquake induced steel structural failures are prevalent due to the high lateral forces applied to the structures resulting in excessive sway and more importantly ultra-low cycle fatigue of structural members. Even though lateral load resisting systems such as concentrically braced frames are installed to the moment resisting frames, ultra-low cycle fatigue induced brace failures play a dominant role in the context of local buckling of the members due to the amplified strains at the vicinity of the brace mid length followed by high strain concentrations. However, the concentric braced frames are designed and detailed deliberately to buckle out of plane in order dissipate the input seismic energy given to the structure by an earthquake. This global buckling of the braces is favorable to a structure in terms of the hysteretic response where the local buckling of the braces drives instant failure of the brace due to ultra-low cycle fatigue fracture. Cyclic void growth models are used to predict this fracture initiation due to ultra-low cycle fatigue in small scale steel components where the method requires a detailed stress and strain history obtained from a meticulous finite element model. If these models are to apply to a case where a multi storey building with braced frames in which an earthquake is applied, analysis of the finite element model to obtained the stress and strain histories until the failure, is quite impossible due to the high computational expense. In this regard, the present study first proposes a new method to model the structural behavior of concentric braces under cyclic loading using fiber beam column elements used in the OpenSees framework and then a new modified cyclic void growth model is proposed. To do that, experimental tests of concentric braces were modeled using OpenSees to observe the applicability and the limitations of fiber beam column element in terms of hysteretic response and strain variation in predicting the ultra-low cycle fatigue fracture. These tests were modeled using OpenSees in such a way, the numerical models fail at the same circumstances as the experimental test and thus validated the hysteretic response asserting the good prediction of global behavior by the numerical model. Penultimately, the resultant stress, strain histories having very low values due to fiber beam column element’s inability of predicting local buckling were used to calibrate a cyclic void growth parameter called modified damageability index. Finally, all the calibrated modified damageability values (λ′) for several experiments were initially found and in future studies, a regression analysis to build a relationship for λ′ in terms of brace geometric parameters such as slenderness ratio and width to thickness ratio to come up with a virgin equation in supporting the new simplified cyclic void growth model will be formulated.

E. M. S. D. Jayasooriya, C. S. Bandara, J. A. S. C. Jayasinghe, K. K. Wijesundara

Incorporation of Disaster Risk Reduction Mechanisms for Flood Hazards into the Greensl® Rating System for Built Environment in Sri Lanka

Global human population continues to boom which consequently necessitates the provision for more buildings. Predominantly in developing countries, these buildings, built to accommodate the influx of more people comply with local and national building laws and regulations which have been outdated and do not resist to natural hazards and rapidly changing natural global trends such as climate change and global warming, etc. Disaster risk in Sri Lanka is increasing mainly due to unplanned urbanization, outdated and poor quality buildings and infrastructure, and the impacts of climate change. This has exposed the community and their economic assets vulnerable to natural hazards such as floods, cyclones, landslides, droughts, coastal erosion and tsunami. Out of those, floods are considered to be the most frequent as well as which destroyed and damaged the highest number of buildings during the period of 1965–2019. As more anthropogenic natural hazards like floods pile up, it is essential that developments, specially buildings which are community shelters, to be disaster resilient and be designed to withstand strains and pressure which will be imposed by future trends. Therefore, sustainable hazard mitigation measures are required to develop a safe, economically feasible, environment-friendly and socially approved growth in Sri Lanka. Although Green Building Council of Sri Lanka (GBCSL) has promoted sustainability and resilience, specifically through reducing resource usage and energy consumption, it has not properly recognized the need of incorporating Disaster Risk Reduction (DRR) mechanisms to withstand against the natural hazards in their GREENSL® Rating System for Built Environment. This research paper is focused on identification of structural and non-structural DRR mechanisms for flood hazards which can be incorporated into the GREENSL® Rating System for Built Environment through refinements to the sub-categories under main 8 categories.

A. A. S. E. Abeysinghe, C. S. Bandara, C. S. A. Siriwardana, R. Haigh, D. Amarathunga, P. B. R. Dissanayake

A Case Study on Early Stage Adoption of Lean Practices in Prefabricated Construction Industry

Prefabricated construction involves the manufacturing of the components off-site or in a separate production facility located on-site. Prefabricated construction industry lends itself easily to new technologies and concepts used in the manufacturing industry. The application of lean concepts to streamline processes by identifying and eliminating wastes in the prefabricated construction is a good example. This paper presents a case study of a real-life industry example of an early-stage adoption of lean practices in prefabricated housing module manufacturer using techniques such as 5S, waste elimination and standard work to improve the productivity of the overall prefabrication process. The challenges of implementing lean practices at a construction setting and possible countermeasures are also presented and discussed. It was observed that even at the early stages of adoption, these lean practices enable better housekeeping, consistent work quality and reliable work processes in the manufacturing facility.

P. A. N. Peiris, F. K. P. Hui, T. Ngo, C. Duffield, M. G. Garcia

Construction Project Managers Graduate Agile Competencies Required to Meet Industry Needs

The construction industry is embracing new management challenges to deal with the ever-increasing needs for collaboration, environmental and social responsibilities. Improvements in construction project management competencies are essential to helping the construction sector to embrace the new challenges. Building engineering management capabilities through the correct training are therefore essential. In research involving the twenty-four largest contractors in Australia ‘Lean construction’ was identified as an important skill to be included in academic programs that has not yet fully been embraced. Contractors are not yet seeing ‘lean’ and ‘agile’ methods as important approaches to improve communication within the teams and between projects. This research highlighted that although contractors identified communication as one of the main skills needed to achieve a good performance in project construction management they do not yet recognise that training in lean and agile methodologies will help them to improve communication not only between professionals but between projects and organisations involved in each project in improving business goals.

Paulo Vaz-Serra, Felix Hui, Lu Aye

Co-created Student Capstone Projects: Case Study of De-Risking Plan for the New Student Precinct

Cross disciplinary team learning enhances the team building and collaborative learning process. Engineering capstone subject provides students with different engineering disciplines to work on a live project. This serves them a great learning experience on collaborative learning and team working. Co-created projects provide students to engage in the project during the planning and construction phases. The new student precinct which is a co-created project, was introduced to the students to work on project management capstone subject at the University of Melbourne. This study presents some findings on teaching and learning outcomes of a co-created projects in engineering management. Students develop great team working and project management skills working in this project and they showed higher engagement in the project as they are considered as one of the main key stake holders in the project.

N. Herath, A. Kennedy, F. Taqi, Z. Dahdoule, F. K. P. Hui, C. Duffield
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