MERCon - 2020
Permanent URI for this collectionhttp://192.248.9.226/handle/123/16315
Browse
Recent Submissions
- item: Conference-Full-text
- item: Conference-Full-text3d full-field deformation measuring technique using digital image correlation(IEEE, 2020-07) Nadarajah, S; Arulkumar, V; Mallikarachchi, C; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPFull-field deformation measurements are crucial as it offers detailed information to better understand both micro and macroscopic nature of material behavior. The practice of employing Digital Image Correlation (DIC) based measuring techniques in experiments has increased due to its ability to generate full-field deformation information with minimal effort. Even though DIC systems are commercially available, the affordability of those systems is questionable in local context due to high capital costs. Most of the past studies related to DIC were focused on testing concrete, masonry and metallic alloy specimens, and little effort has been made on materials with recoverable large elongations. This paper presents a 3D fullfield deformation measuring system that has been developed with a special focus on hyperelastic materials. The proposed system requires two common digital cameras for image acquisition, as the depth information is of interest. Images are then processed using the MATLAB-based algorithm developed to produce the full-field deformation map. Hyperelastic specimens of two different thicknesses were tested over 70% strain and the accuracy of the strain measurement using the proposed system is validated against physical measurements. The results have shown that the strains can be captured to an accuracy greater than 90% using the proposed technique.
- item: Conference-Full-textBond-slip models of cfrp/steel double strap joints subjected to long term exposure of moisture and elevated temperature(IEEE, 2020-07) Perera, UND; Chandrathilake, ERK; Gamage, JCPH; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPStrengthening of deteriorated steel elements using Carbon Fiber Reinforced Polymer (CFRP) materials is widely gaining appeal. Since the majority of applications can be seen in outdoor structures, the evaluation of long-term behaviour under various environmental conditions is an important aspect. In the present study, the bond performance of CFRP strengthened steel double strap joints immersed in distilled water at ambient (28 oC) and elevated (40 oC) temperatures for six months was examined. A total of twelve specimens were tested including four control specimens and eight number of conditioned specimens. A numerical model was also developed. The model results are in good agreement with experimental results. The bond shear stress – local slip curves were then developed for each environmental condition using model predicted strain readings. The bond-slip models showed a bond shear strength degradation of about 24 % at 28 oC and 30 % at 40 oC within the exposure duration of six months.
- item: Conference-Full-textStudy on bamboo and steel as hybrid reinforcement for concrete slab(IEEE, 2020-07) Parasuram, M; Baskaran, K; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPFor a developing country like Sri Lanka, imported construction material like steel is not cost-effective. The increasing trend in demand for construction material leads to an increase in the consumption of natural resources as well. So, to reduce the steel usage, bamboo can be used as hybrid reinforcement to achieve the benefits of both steel and bamboo, while compensating the disadvantages of each other. Bamboo is selected because of its high tensile strength to weight ratio, less carbon footprint, and rapidly growing ability. In this paper, details of the study carried out to analyze the behavior of three concrete slabs reinforced with steel and bamboo in comparison with the steel alone (control slab) is presented. All four slab specimens with dimensions of 1200 mm * 1200 mm* 60 mm were cast and tested under centerline loading. Flexural behavior of control slab reinforced with steel alone was compared with 3 hybrid-slabs reinforced with a different combination of steel and bamboo. The experimental results of 4 slabs were comparably similar, and these results were used to validate some numerical models too (developed in Midas software). It is concluded that steel and bamboo reinforced hybrid slabs can be used as an effective alternative.
- item: Conference-Full-textEmbodied energy and carbon footprint of two storied refuge space with lightweight load bearing panels(IEEE, 2020-07) Thevarajah, BE; Jayasinghe, MTR; Lewangamage, CS; Ibell, TJ; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPWith the effects of climate change, natural disasters are becoming more severe and frequent. Disaster resistant structures play a vital role in preventing loss of lives and damage to the belongings. A suitable material that could resist the forces of nature needs to be selected to ensure safety while reducing the adverse effects on the environment. Turning waste material into raw material is welcomed as the scarcity of natural resources and disposal of waste are becoming major issues nowadays. Such a method of replacing coarse aggregate with 100% recycled Expanded-polystyrene (EPS) is the production of lightweight concrete wall panels. A new trend of lightweight panels can be widely seen as partitions in reinforced concrete frame buildings. Incorporating these panels as a loadbearing element would lead to a drastic change in the industry. Hence a detailed study has been carried out to find out the properties of EPS panels with respect to embodied energy and carbon footprint. A comparative study has been conducted between two-storied refuge space with lightweight load-bearing panels and conventional materials such as cement blocks and fired clay bricks, through which the potential of lightweight wall panels as load-bearing walls for a two-storied refuge space is assessed.
- item: Conference-Full-textStrengthening of damaged out of plane curved reinforced concrete beam using carbon fiber reinforced polymer(IEEE, 2020-07) Kulendren, S; Fernando, C; Gamage, P; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPCurved major structures will get cracks and it will be costly and difficult to replace. So retrofitting technique in this paper will enable the engineers to retrofit these beams without replacing them. This experimental study aims at investigating the behaviour of damaged curved Reinforced Concrete (RC) beams strengthened with Carbon Fiber Reinforced Polymer (CFRP) sheets. Two sets of curved RC beam specimens, with 4000 mm radii were used. The beams were pre cracked and repaired by using epoxy grout prior to strengthening. The beams were retrofitted using an alternative bond arrangement of Near Surface Mounted (NSM) CFRP sheets. The specimens were tested under four-point bending test method. On average 51% increase in flexural gain was observed from retrofitted beams with respect to non-cracked control samples.
- item: Conference-Full-textInfluence of intersected fold-lines on thin-folded membranes(IEEE, 2020-07) Piyumi, C; Mallikarachchi, C; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPConcept of solar sailing which uses solar energy to propel a spacecraft is becoming popular as a low-cost spacecraft propulsion system. These solar sails require larger area while in operation and are stored in the limited space available in launch vehicles by introducing series of fold-lines. Therefore, precise prediction of deployment behaviour is important in designing tear-free deployment configurations. Physical testing of such applications is difficult due to presence of gravity, air drag and friction which prevent such structures from deploying on Earth. Hence deployment of solar sails has to be tested under vacuum and zero gravity conditions. Virtual simulations are being used to overcome these challenges. This paper attempts to understand deployment behaviour of highly compacted thin membranes and highlight the importance of incorporating fold-line properties in finite element modelling. The effects of membrane thickness and creased geometry for the deployment behaviour and deployment force were also studied through force–displacement relationship of the membrane opening. It is shown that the connection with rotational stiffness gives better idealization for the fold-line in virtual environment. Further it is evident that the deployment force and shape have a significant influence from membrane thickness and fold-line geometry.
- item: Conference-Full-textparametric study on the homogenized response of woven carbon fibre composites(IEEE, 2020-07) Herath, S; Jayasekara, M; Mallikarachchi, C; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPUltra-thin woven fibre composites are becoming popular in a wide range of weight-sensitive applications and hence it is important to predict their mechanical properties for accurate analysis and design purposes. This paper presents a parametric study on the homogenized response of two-ply plain woven carbon fibre composites. Influence of volume fractions, traction coefficients and fibre/resin material parameters on the laminate stiffness matrix (ABD) entries were investigated. For this study, a parametric representative unit cell is generated using a finite element pre-processor, TexGen and a Matlab based algorithm. An automated algorithmic computation of the laminate stiffness matrix is used to study its variations for different combinations of uncertain parameters. Such variations are compared with the experimental results to learn the possible reasons for the observed deviations between experimental and numerical results. It is shown that the volume fractions linearly scale the laminate stiffness entries, though interestingly, each entry has a unique scaling factor.
- item: Conference-Full-textStudy on concrete filled steel circular and square tubes(IEEE, 2020-07) Bogahawaththa, PBMR; Madhuranga, KP; Hidallana-Gamage, HD; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPConcrete filled steel tube (CFST) is a composite material which is increasingly used in the civil engineering industry. So, it is required to identify the properties of concretefilled steel tubes as a composite material. This paper focuses on a study conducted on concrete-filled circular steel tubes and galvanised square sections. Concrete filled circular steel tubes were tested under axial compression with three different diameter-to-thickness (D/t) ratios and two different concrete compressive strengths since CFSTs are most effective as compression members. Galvanised steel square sections were also tested for compression capacity and failure mode. Finite element model was developed using the ABAQUS software and two experimental programmes were carried out to find material properties of concrete and steel for finite element modelling and two experimental programmes were carried out to verify the finite element modelling. Galvanised iron square sections were modelled using MIDAS gen software and verified with experimental results for the failure load and failure mode also. The axial capacity of CFST was found theoretically using two different codes and one equation found in the literature. Experimental as well as numerical results showed that the axial capacity of CFST increases as the concrete infill increases and decreases with D/t ratios.
- item: Conference-Full-textHolistic behaviour of urban pond systems for flood risk mitigation- a case study in metro Colombo area(IEEE, 2020-07) Ponnamperuma, N; Rajapakse, L; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPIn every year Colombo becomes a flood victim causing many negative effects and the current flood control systems are inadequate to address the issue to the fullest. This case study is to enhance the present flood mitigation system in Colombo. Methodology development was targeted for evaluation of the effectiveness of cascade behavior of ponds in flood mitigation. Initially, a pond system with cascade connectivity was identified in the Metro Colombo flood affected area and pond capacities, streamline network and catchment area of each pond were generated using Digital Elevation Model(DEM) and GIS software. Stream inflows were developed using 5-year storm event from IDF curves for Colombo and HEC-HMS software. Simulation of ponds during rainfall event was modelled using HEC-ResSim software and outflows were obtained for both isolated and cascade behavior of ponds. Flood maps of each pond for both cases were modelled using HECRAS software. Total flood inundation area of the 5-year storm event when the ponds are acting as isolated flood resisting structures and under holistic behavior is 74.7 ha and 63.9 ha respectively. Thus, the reduction of inundation area when the ponds are connected as a cascade is 10.8 ha which is 14.47% of the total inundation area.
- item: Conference-Full-textFeasibility of robotic technology for the advancement of construction industry in Sri Lanka(IEEE, 2020-07) Gamlath, M; Waidyasekara, KGAS; Pandithawatta, S; Weeraddana, CUS; Edussooriya, CUS; Abeysooriya, RPInnovative technologies are vital contributors to enhance the performance level of the construction process and products. Substantial economic benefits can be generated by implementing these innovative technologies. The construction industry is traditionally not being a desirable area for robotics application. However, with the discovery of more cost-effective applications and motives such as lack of labor population, the aging skilled workers, and safety issues, the use of robotics will undoubtedly increase. However, the fully-geared and advanced technological applications are still not implementing within the Sri Lankan construction industry, other than the basic applications that provide visible benefits. Therefore, there is a need to investigate the feasibility of introducing robotic technology to enhance the quality of the Sri Lankan construction industry. Hence, this paper aims to review the current application level of robotic technology and analyze its feasibility in the local construction industry. The research aim was achieved through a quantitative approach. A detailed questionnaire survey was carried out among subject-related professionals, and analysis was done with the descriptive statistical analysis technique. The feasibility of implementing robotics is evaluated through six primary feasibility criteria, identified as cost-effectiveness and economy, safety, social, productivity, quality, and technology.
- item: Conference-Full-textExamining the community perception towards communication modes of issuing multi-hazard early warning (mhew) in Sri Lanka(IEEE, 2020-07) Shehara, PLAI; Siriwardana, CSA; Amaratunga, D; Haigh, R; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPCommunication modes are considered important in the effective delivery of Multi-Hazard Early Warnings (MHEW) to the downstream community level. More significantly, in the global context, the lack of having proper communication modes and resistance of the community to adapt to novel technologically based communication modes have identified. Indian Ocean Tsunami which hit in 2004 is a crucial disaster incident where the lack of having effective communication modes for the warning dissemination emerged in many of the affected countries. To identify the community level perception on the existing communication modes in Sri Lanka, a field questionnaire survey was developed and conducted among 10 Grama Niladari divisions in the country and overall 323 community responses were obtained. As per the results obtained under the response analysis, traditional modes of communication were highlighted as the most effective communication mode both in urban and rural levels, among both males and females, and among each of the age category distribution. Further, the community perception level was indicated based on the mean perception score and sentimental perception score on the mobile-based communication platforms. This denoted that the community perception level is at a lower level over the warning dissemination through mobile-based platforms.
- item: Conference-Full-textStructural mechanics analogies for a resilience audit and index(IEEE, 2020-07) Dias, P; Viswakula, S; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPThe World Economic Forum’s (WEF) Global Risks Report 2013 arrived at a working definition for national resilience that involved three characteristics, namely robustness, redundancy and resourcefulness. We have drawn mappings between the WEF’s robustness, resilience and resourcefulness and the structural engineering characteristics of robustness, redundancy and ductility. We use this first to propose a multi-sectoral framework involving the infrastructural, environmental, sociological, economic, and geopolitical sectors, also proposed by the WEF, but divide them into the three hierarchical levels of country, city and building. These three levels, three characteristics and five sectors give rise to a matrix of 45 aspects, with resilience features suggested for some of them. In this way we move towards proposing a multisectoral, multi-hierarchical resilience audit for a nation. We then use force-displacement analogies from structural mechanics to quantify resilience through an analogy to energy absorption, depending on the various levels of robustness, redundancy and ductility, thus generating an 8-point scale for a resilience index. The analogy suggests that ductility is the most important characteristic, but that it can be traded-off with redundancy. Redundancy is more important than robustness, but both are much more important for systems that lack ductility compared to those that possess it.
- item: Conference-Full-textDevelopment of low-cost wireless sensor network and online data repository system for time synchronous monitoring of civil infrastructures(IEEE, 2020-07) Vishnu, P; Lewangamage, CS; Jayasinghe, MTR; Kumara, KJC; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPAdvances in wireless sensor networks (WSN) are well proven and commonly used in Structural Health Monitoring (SHM). SHM using WSN is the modern paradigm which incorporates automated systems for data acquisition, in monitoring, analysis, and identification of structural responses and defects. Even though currently used WSN are economical compared to tethered monitoring systems, it is still unaffordable. The costly nature of traditional data loggers and the low penetration nature of currently used networking protocols, through civil structures thus requiring dense array of sensors, increase the overall cost of a WSN. This paper discusses the development of a low cost WSN to monitor the acceleration response of civil engineering structures using off the shelf products. The developed system is capable of capturing synchronous acceleration response data with the sampling frequency of 100 Hz with a resolution of 0.5 mg. The collected data is processed and shared between peer nodes using sub 1 Gigahertz wireless protocol, and stored within an online based central data repository system replacing traditional data loggers. The developed low cost WSN is proved to be a better low cost alternative in the context of a target building with 48 floors (185 m height).
- item: Conference-Full-textInvestigation on the mechanical property variation on timber caused due to the thermal and chemical modification(IEEE, 2020-07) Sudeshika, DMP; Mendis, MS; Halwatura, RU; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPTimber is a popular natural construction material since ancient time. Quality of timber varies with physical and mechanical properties. Timber modification techniques are used to improve durability and dimension stability of the timber. The aim of this research is to create a data base on mechanical property variation on timber caused due to the thermal and chemical modifications. Two distinct industrial surveys were conducted clusters-based and companies based survey to identify most abundantly utilized timber for structural applications and most abundantly utilized preservative techniques in Sri Lanka. Through the industrial survey results, three timber species were selected and specimens were prepared. Industrial survey concluded five major treatment methods; kiln dry,dipping,impregnation,brushing and spraying. Then prepared specimens were treated by the above timber modifications techniques. Compression parallel to grain and static bending test (central loading) were conducted according to BS 373: 1957 standard. According to test results, in Alastonia timber dipping & kiln dry and impregnation & kiln dry, in Rubber timber kiln dry, dipping & kiln dry and dipping and in Mango timber brushing and spraying modification techniques exemplified significant mechanical properties (compression parallel to grain,MOR (modulus of rupture) and elasticity) improvement
- item: Conference-Full-textA preliminary study on fabric formwork for a mud-concrete slab system(IEEE, 2020-07) Suluxan, S; Nanayakkara, I; Arooz, R; Halwatura, RU; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPMud concrete and fabric formwork are existing technologies in construction industry which are gaining importance with the drive towards a climate conscious construction industry. The current work aims at combining these two technologies toward developing an earthen slab system. A preliminary study was done to assess the viability of fabric formwork for mud-concrete casting and identify potential challenges in developing such a technology. A series of tests were done to identify the performance of commonly available grey fabric ('amu redi') with changing unsupported span lengths of fabric, thickness of overburden mud-concrete layers, and water content of the mud-concrete wet mix. The experimental work verified the viability of using commonly available fabric as formwork for typical mud concrete mixes. The study showed an upper bound on the thickness of the overburden mud concrete layer beyond which the influence on the fabric, measured as the maximum deflection, was negligible as arching effects transfers the loads laterally. A peak water content at which the maximum deflection of the fabric was the highest was observed. In addition, the use of fabric formwork was observed to give a smoother surface finish.
- item: Conference-Full-textDevelopment of foam concrete blocks with bottom ash(IEEE, 2020-07) Fonseka, I; Nanayakkara, A; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPBottom ash, which is a byproduct of coal fired thermal power plants has given rise to major environmental impacts due to its potential hazardous effects. Through this research, attempts were made to use bottom ash as a substitute for river sand in producing foam concrete blocks. This will further contribute to the reduction of excessive river sand mining. In this research main focus was given to develop lightweight concrete blocks incorporating bottom ash and foaming agent. Experimental investigations were carried out by varying bottom ash to cement ratio, water to cement ratio and particle sizes of bottom ash in order to identify the potential of applicability of bottom ash in producing foam concrete blocks. Furthermore, in this study, wet method was used to generate foam by using industrial foam generating machine. By evaluating a range of properties such as compressive strength, drying shrinkage, wetting expansion and water absorption, it was found that the optimum bottom ash to cement ratio for foam concrete is 0.75 which resulted in compressive strength of 3.8 MPa with dry density in the range of 700-850 kgm-3 which satisfies the requirements of lightweight category masonry blocks.
- item: Conference-Full-textInvestigation of fungus growth and moss growth on different wall care putty materials along with different walling materials(IEEE, 2020-07) Gunawardanaa, SAA; Galkanda, GAHH; Halwatura, RU; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPCement and sand are two of the materials which are used in the infrastructure development and are also main components of masonry coatings. Nevertheless, negative impacts indicated by these materials are crucial. Cement production accounts for considerable amount of global CO2 emissions while sand mining activities disturb the natural equilibrium. However, cement and sand consumption can be considerably reduced by omitting wall plastering. In order to accomplish the requirement of smoothing the wall, application of wall care putty materials to an unplastered wall can be considered as a sustainable solution. This research study was conducted to investigate the fungus growth and moss growth on different wall care putty materials along with different walling materials. Four types of walling materials and ten types of wall care putty mixtures were selected. Fungus growth and moss growth were conducted in controlled environment to accelerate fungus growth and moss growth on wall care putty materials. Results of this study showed that wall care putty mixtures were not prone to fungus growth under tropical climatic conditions. Moss growth was present on wall care putty mixtures and there was an impact from the walling material to the growth of moss on the surface of putty application
- item: Conference-Full-textInvestigation of mechanical properties of mud concrete with coconut fiber reinforcement(IEEE, 2020-07) Galabada, H; Galabada, PD; Galkanda, H; Halwatura, RU; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPMud concrete was a sustainable innovation, invented to replace existing conventional construction materials with sustainable material. Mud concrete consists of soil and cement along with water. In terms of sustainable construction, cement which act as the stabilizer in mud concrete should be kept lesser as much as possible, according to its potential environmental issues. Therefore, evaluation of ability to enhance the mud concrete properties by adding some admixtures is essential. There are no of admixtures used in the construction industry with many forms, such as liquid, solid, semisolid or fiber. In most of the studies fiber was used as an admixture to improve the strength performance of construction materials. Hence, evaluate the strength performance of mud concrete with fiber is important to reduce cement in sustainability contest. Therefore, this study was investigated the effect of natural fiber length on compressive strength and strength variation with water content of mud concrete with fiber. According to the results, the highest strength was recorded with the fiber length of 60 mm and the compressive strength was decreasing with the increasing water content. The study concluded that the optimum fiber length is 60 mm and there is a negative correlation between compressive strength and water content.
- item: Conference-Full-textStudy on use of glass in Sri Lankan construction industry(IEEE, 2020-07) Fowza, MJF; Gamage, HDH; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RPThis paper studies current practices of designing glass facades/ windows in Sri Lanka. Glass facades/ windows in Sri Lanka are currently designed by using the design standards developed for other countries or by using thumb rules. Since there are no any detailed investigations to see the accuracy of these thumb rules, the results given by thumb rules may be overdesigned or under-designed. In this research a questionnaire survey was conducted to identify different glass types and their usage, thumb rules, design standards and reasons for failures in glass structures. Experiments were done to ensure the strength of the glass and Aluminium available in Sri Lanka. A guideline was developed for four-point pin supported glass panels to determine the required glass thickness under the applied load. Those have been developed based on the comprehensive numerical analysis conducted using SAP2000 finite element software. This research will therefore enable the design engineers to select the required glass thickness by applying specific load cases for the safe and economical design of glazed facades/ windows to suit the local conditions.