MERCon - 2022

Permanent URI for this collectionhttp://192.248.9.226/handle/123/18494

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Moratuwa Engineering Research Conference 2022 [Pre Text]
(IEEE, 2022) Rathnayake, M; Adhikariwattage, V
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Modelling and simulation of a vertically integrated zinc oxide piezoelectric nanogenerator
(IEEE, 2022) Vithusan, T; Nashira, MNF; Adikary, SU; Rathnayake, M; Adhikariwattage, V
Due to recent developments in energy harvesting, there has been a subsequent rise in MEMS (Micro electromechanical systems) powered by low-frequency vibrations in the environment through effective transduction procedures like piezoelectricity. In this paper, a vertically integrated single piezoelectric Zinc Oxide nanowire-based system is modelled for energy harvesting applications. To reinforce this development, different structures of nanogenerators were modelled and simulated using COMSOL Multiphysics 5.3 software for their performance upgrades. It was developed to analyse the compression and bending effect of the nanowire. To compare and validate the induced piezoelectric output, mathematical equations were derived using piezoelectric constitutive equations. Moreover, the voltage output of the nanowire under a constant lateral force was analysed varying with the nanowire dimensions in terms of aspect ratio. The analysis results have shown that the compression of ZnO nanowire gives more output voltage compared to the bending of the nanowire for the same nanogenerator. The theoretical and simulation results also prove that the length of the nanowire does not influence the piezoelectric potential in a lateral bent nanowire.
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Study of degradation behavior of ASA coated PVC roofing sheets
(IEEE, 2022) Udayanga, S; Weragoda, SC; Alahapperuma, KG; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Polyvinyl Chloride (PVC) based roofing sheets are widely used in industrial and domestic applications today. It is recognized that ultraviolet rays (UV) in sunlight (wavelengths between 280 nm and 400 nm) cause photodegradation of some organic materials including polymers. Therefore, studying the change in properties of PVC/Acrylonitrile Styrene Acrylate (ASA) roofing sheets due to weathering is essential for their successful application. From this study, it was attempted to study how photodegradation affects some properties like hardness and impact strength of the roofing sheet. It was evident from the UV exposure test data that prolonged exposure to UV radiation deteriorates the hardness and impact strength properties of the sheet. But no change in appearance was observed in both UV exposure test and accelerated weathering test.
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Value engineering as a pragmatic value enhancing tool for public sector construction projects
(IEEE, 2022-07) Anuradha, IGN; Ambagala, APKK; Dharmarathne, PD; Liyanage, SU; Halwatura, RU; Devapriya, KAK; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Value Engineering is a globally accepted methodical approach that enables the best balance between the quality, performance and reliability of a project while improving the “value” of goods, products and services. The concept of Value Engineering is applied within the construction industry of many countries to improve the output comparing to conventional practice. Most importantly, adopting conventional practice reasons for less value for the resources use for the construction projects. This is quiet high in public sector projects. Therefore, applying Value Engineering for public sector projects, will give better value for the resources use. Nevertheless, the applications of Value Engineering in public sector construction projects of Sri Lanka are rare. Therefore, this study aimed to identify the challenges that affect the implementation of Value Engineering for the public sector construction projects in Sri Lanka. In order to achieve the above aim, two objectives were implemented as (1) identify the significance of Value Engineering and the challenges affecting to the implementation of Value Engineering for the public sector construction projects in Sri Lanka, and (2) to develop a suitable framework to overcome the challenges affecting the implementation of Value Engineering in public sector construction projects. 23 challenges were identified through a comprehensive literature review and a questionnaire survey was conducted to identify the impact of those challenges and to find out suitable strategies to overcome them. There the data were collected from 71 construction industry professionals with Value Engineering knowledge. Then, the RII technique was adopted to rank the challenges based on the collected data. Eventually, based on the challenges and the proposed strategies a framework was developed for better adaptation of Value Engineering for the public sector construction projects in Sri Lanka.
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Appraising vulnerabilities on elders and built environment of aging-in-place in tropics using infrared thermography
(IEEE, 2022-07) Rajapaksha, I; Jayasekara, R; Siriwardana, C; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Demographic shifts due to the burgeoning ageing population and increasing global temperatures are synchronized societal challenges of the future. People living in low and middle-income countries are ageing much faster than richer countries and over the next three decades, ageing is predominant in Asia. People ageing in low-income communities of the tropics will become more vulnerable to heat with limitations and conditions of the houses they live. Thus, the study appraises the vulnerabilities of elders and the built environment of aging in place in the tropical city of Colombo, Sri Lanka. The selected cohort is permanently residing in a low-income community. Infrared thermal imagery analysis of elders is evident for a mean skin temperature of 34.9° C, which is 1.9° C above a healthy adult. Mean skin temperature further increases in elders living in detached houses. Moreover, the houses demonstrate poor ventilation, and overheated interiors with less usable floor area and windows. Additionally, the elders are suffering from long-term illnesses and their income restricts treatments. Thus, the study portrays an overarching social injustice status of ageing population in cities in Sri Lanka, as elders prefer aging in place. Thus, it highlights the significance of physical attributes of built environment to ensure healthy aging in warming climates.
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Development of a cost-optimized model for evacuation route planning for tsunamis
(IEEE, 2022-07) Kannangara, KKCL; Adhikariwatte, V; Siriwardana, CSA; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
This paper addresses the problem of planning inland evacuation routes along a given coastal stretch. This study presents a methodology to determine the optimum interval for proving inland evacuation routes within a stretch of vulnerable coastal area. It is evident that the developing countries may face financial constraints while providing necessary infrastructure facilities to minimize the fatalities. The establishment of evacuation routes or structures involves expensive capital and maintenance costs. Policymakers need a scientific basis to evaluate the provision of infrastructure facilities as part of planning emergency response strategies. The proposed methodology looks at the trade-off between the cost of providing infrastructure for evacuation and the cost of exposure to the risk. A total cost model is derived as the sum of infrastructure cost and cost of people being exposed to the risk as a function of uniform spacing between inland evacuation routes. The optimum uniform spacing that minimizes the total cost is derived. Thus, the spacing between evacuation routes is obtained as a function of the value of time saved from exposure to the risk, population density in the area, hazard zone depth, walking speed of individuals, and cost of infrastructure. Thus, the derived model is applied to a case study in Thelwaththa Grama Niladhari Division (GND), located in the southern province of Sri Lanka, which was severely affected by the 2004 tsunami event.
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A Conceptual framework to understand the multi-hazard early warning mechanism in communication management
(IEEE, 2022-07) Shehara, PLAI; Siriwardana, CSA; Amaratunga, D; Haigh, R; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
A conceptual model development is a primary mechanism for defining dependencies among parameters. Here, the integration of concepts linked with Multi-Hazard Early Warning mechanism is captured. This became more significant when implementing Disaster Risk Reduction strategies emphasized by the Sendai Framework for Disaster Risk Reduction 2015-2030. Such a warning mechanism is required to ensure that the public at risk is timely alerted and adequately informed. In proper understanding of this mechanism, the conceptual model development is a significant approach. Here, the activity level sequencing was determined with the analytical illustration of the activity concentration and stakeholder level. Recent studies were considered in conceptual model development. For further verification, the reviews obtained from the pilot expert survey were considered. The developed model was checked for applicability considering disaster situations such as Indian Ocean Tsunami in 2004, Cyclone Fani in 2019 and Meethotamulla garbage dump failure in 2017. Here, the activity level concentration variation is categorized based on stakeholder levels which define on the international to community level are captured along with time change. Based on the idealized conceptual framework, the policymakers and associated stakeholders can use this in integrating the guidelines and policy framework which are targeted at Disaster Risk Reduction.
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Understanding the interdependency of resilience indicators in green building assessment tools in Sri Lanka: an application of swara method
(IEEE, 2022-07) Rajapaksha, SH; Rajapaksha, DV; Siriwardana, C; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Sri Lanka is frequently subjected to disasters caused by adverse natural shocks and climatic stresses. Climate change which is accelerated by Green House Gases is a main cause behind the more frequent and intense disasters. Hence, the construction industry is now heading towards Green Buildings as one of the sustainable aspects. Since the involvement in the green building industry in Sri Lanka as well, it has emphasized the importance of incorporating disaster resilience indicators into Green Building Rating Tools (GBRTs) to ensure that green buildings can withstand adverse natural shocks and climatic stresses while maintaining their long-term survivability. There have been various disputes over the concepts “disaster resilience” and “sustainable development,” which have impeded implementation. Therefore, in this research, a multicriteria decision-making tool, the Stepwise Weight Assessment Ratio Analysis (SWARA) method was used to identify the overall impact of the integration of disaster resilience indicators into a green building framework. It was intended to capture different perspectives of decision makers on each possible disaster resilience aspect that can be integrated into a GBRT related to the Sri Lankan context. The most suitable resilience indicators were selected from the GBRTs and related studies and used in the evaluation. They were assessed for their significance in enhancing disaster resilience as well as the sustainability of green buildings. The results have shown that risk avoidance related indicators can enhance the disaster resilience of the building while increasing the sustainability. Conversely, disaster resilience indicators like improved structural and architectural aspects, and excessive use of hazard-resilient and more robust materials can reduce the overall sustainability of a green building.
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3D full-field deformation measurement using stereo vision
(IEEE, 2022-07) Sarma, LS; Mallikarachchi, C; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Measuring 3D deformation and strain are crucial parameters in structural engineering applications both at the construction and operational stages. Precise 3D full-field measurements are useful in structural optimization, damage detection and retrofitting. Digital Image Correlation is a non-contact optic-based measurement technique that is proven to be an ideal candidate in this regard. It has the potential to become a cheap, simple, and precise solution for deformation measurement. However, the currently available Digital Image Correlation measuring systems require expensive dedicated software packages and physical resources which are difficult to access. Therefore, there is a need to develop a cost-effective measuring technique to effectively use it in the local context. This research focuses on the development and validation of a precise non-contact-based deformation measurement technique. In the proposed method, 3D full-field deformation of the deforming object is measured by processing stereo photographs taken with commonly available digital cameras using the image processing toolbox available in the MATLAB commercial package. Further, the proposed method is enhanced by developing it as a standalone application, which can be installed and conveniently used by any technician. Capability of using the developed application in common civil engineering laboratory experiments has been demonstrated.
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Study on honeycombs in structural concrete elements
(IEEE, 2022-07) Kuruppu, KABP; Nanthakumar, M; Baskaran, K; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Concrete structures are subjected to various types of surface defects such as honeycombs, surface voids, form streaking, etc. Proper understanding of the root causes of each type of defect is significant in preventing recurrence as well as applying remedies. An extensive field survey was conducted in connection with the construction sector of Sri Lanka to gather information on the current practices. It was found that the construction industry needs more awareness on correct practices. This study attempts to fill the gap between current field practices and standard practices. Poor workmanship in consolidation of fresh concrete leads to most of the defects, but this study shows how the understanding of technical background of each activity and the proper planning at initial stages contribute to effortless improvements in workmanship. Contradictions between codes of practices for design of reinforced concrete and codes of practices for consolidation of concrete were taken into consideration under this study. In order to identify the locations of hidden honeycombs, a series of UPV tests (conventional approach) were performed, quantitative and qualitative analysis of them has been provided under this study. It has shown the importance of moving to modern non-destructive evaluation approaches for such scenarios.
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Investigation of the feasibility of prestressed concrete (PC) over conventional reinforced concrete (RC) in water retaining structures
(IEEE, 2022-07) Chathuri Madhushani, WLA; Hidallana-Gamage, HD; Baskaran, K; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Concrete water tanks are used to store and supply safe drinking water and are designed as crack-free structures. The demand for water tanks will continue to increase in the coming years; quick construction methods and economical design approaches will be helpful in the selection of water tanks for relevant applications. Prestressed Concrete (PC) will be a better alternative for Reinforced Concrete (RC) water tanks which are commonly used in Sri Lanka. This paper presents design guidance for PC circular water tanks resting on the ground. The design and construction approaches for PC circular water tanks were identified following EN 1992-1-1:2004 and EN 1992-3:2006 standards. The Midas FEA Finite Element (FE) software was used to analyse the tanks. The economic feasibility of both PC and RC tanks is compared for different tank capacities. The design outputs were converted into structural drawings and bills of quantities. Results of the material take-offs showed that RC is economical only for 4500m 3 or less capacity. For higher capacities (above 4500 m3), PC tanks become cheaper by around 12-14%. The information presented in this paper will therefore be helpful to understand the design philosophy for the safe and economical design of water tanks with better crack control.
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Case studies on blast behaviour of glass façades: Sri Lanka easter bombings
(IEEE, 2022-07) Jayaweera, GCS; Hidallana-Gamage, HD; Baleshan, B; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Sri Lanka Easter attacks were done by coordinated suicide bombers on 21 st of April, 2019. This paper investigates the damages to the glass façades due to the explosions that occurred inside the five-star hotels, Shangri-La, and Kingsbury in central Colombo. It is evident from previous explosions that the blast-related injuries are mainly caused by the free-flying glass fragments. Laminated Glass (LG) will provide better resistance to explosions that occur outside the building if they are properly designed to be held on the supporting structure. Because, if the blast pressure enters the building, it will cause severe damage to the building elements while creating injuries to the occupants. However, when an explosion occurs inside the building, damage to the building elements and occupants will be severe if the blast pressure cannot escape from the confined building premises easily. Therefore, both of these aspects should be considered when designing glass façades for a credible blast load. LG has better blast resistance than monolithic glass. This paper presents a comprehensive review on the effect of the Easter bombings on glass façades and some design strategies which can be recommended for blast-resistant glazing with the evidence from available literature and design standards.
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Design optimization of a steel bridge bracket
(IEEE, 2022-07) Liyanagunawardhana, S; Sarma, LS; Herath, S; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Steel brackets have a renowned potential of being used in bridge constructions as a load-bearing element. However, the excessive material usage in bracket manufacturing will lead to expensive constructions, increased energy consumption and a rise in carbon footprint. To circumvent these challenges, this paper demonstrates a novel approach for producing an optimum and sustainable steel bracket for pedestrian bridge construction. Topology optimization is used as the tool of choice in this work, which has a proven record of arriving at the highest stiffness to weight ratio. This study uses an existing steel bridge bracket in Castleford Foot Bridge, England as a study case. The bracket is optimized under several volume fractions and ultimately, the optimum design is selected based on both simulation results and practical considerations. It is shown that a considerable amount of material could be saved without sacrificing the strength and stiffness requirement of the bridge bracket. Without a loss of generality, the selected optimal design is manually extracted to a Computer-Aided Design (CAD) software for further post-processing and analysis.
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Homogenization of ultra thin woven composite structures at high curvatures
(IEEE, 2022-07) Weerasinghe, U; Herath, S; Mallikarachchi, C; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Growing demand for ultra-thin woven composites has been identified in weight-sensitive applications, especially in space engineering applications such as self-deployable structures. They undergo extreme curvatures during folding and deployment process and hence understanding their mechanical behaviour is important for optimization of future structures. Literature on experimental studies unfolds that there is a considerable reduction in bending stiffness of these ultra-thin woven composites when subjected to curvatures. This paper presents a numerical investigation that incorporates inter-tow and inter-lamina interaction behaviour on the homogenized response of a two-ply plain woven carbon fibre composite. Two distinct models were used in the analysis with dry fibre approach and resin embedded geometry. The analysis is advanced further towards the non-linear regime to predict the response under higher curvatures. It is shown that the developed models are capable of capturing the reduction in flexural stiffness.
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Rapid risk assessment of Sri Lankan school buildings against tsunamis
(IEEE, 2022-07) Nawanandana, C; Dias, P; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Rapid assessment of building vulnerability and risk is very useful, especially if based on sound engineering principles as opposed to expert opinion alone. A tsunami relative risk index (TRRI) has recently been proposed for hospital buildings based on such an approach. This study extends the concept to reinforced concrete school buildings. Two typical plan forms of school buildings were explored, each of two and three storey height. The criterion for overall structural failure was the shear capacity of columns; for scour, the number of footings undermined; and for debris impact, the shear capacity of corner columns. Of the parameters explored, the inundation depth and flow velocity were found to have the greatest influence on TRRI, while building type, building height and flow direction had much smaller influence. Debris impact was the governing risk at low inundation depths (around 1m), with scour at medium depths (around 3m) and overall structural shear failure at higher depths (around 5m).
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The use of plastic aggregate in concrete
(IEEE, 2022-07) Ameen, SAZ; Karunaratne, S; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Plastic waste management is a growing concern worldwide since permanent solutions are costly for third-world countries. This study explores storing plastic waste in concrete as a partial replacement of the fine aggregate to produce a useful building material. To resolve the material's lack of compressive strength, this study used HDPE chemically treated with Sodium Hypochlorite (NaOCl) and partially replaced the cement with silica fume at 7.5%, and 10% to improve the concretes Interfacial Transition Zones (ITZ). This research tests the workability, density, and compressive strength, and completes a microstructure analysis of this material to determine if structural lightweight concrete (SLWC) can be produced. The results obtained indicate that adding silica fume with chemically treated aggregate increased the compressive strength by 1.9% and 7.4% respectively in comparison to the control. Through the statistical analysis, these additions were then shown to make a significant difference in the concrete's strength. The microstructure analysis too confirmed that the quality of the ITZs had improved in these mixtures. However, the workability of these 2 mixtures was reduced by 77.4%. The study concludes that although the concrete isn't lightweight, its compressive strength can be improved to match that of conventional structural concrete.
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Investigation of replacing aggregate with non-homogeneous waste tire rubber aggregate in concrete
(IEEE, 2022-07) Kuruwita Arachchi, VI; Gamage, JCPH; Selvaranjan, K; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
This article investigates the impact of using non-homogenous rubber aggregate on a developed concrete mix design. Identifying the dominant reasons and modifications to be made to improve the properties of rubberized concrete are discussed with respect to the diverse number of literatures. The recycled waste tire rubber particles were tested to identify the physical properties of rubber aggregate and twelve rubberized concrete cubes were tested in axial compression. The cubes were produced by replacing waste tire rubber with 1) 0% aggregate volume (Series 1) 2) 20% fine aggregate volume (Series 2) and 3) 10% coarse and 10% fine aggregates of the total aggregate volume (Series 3). The results show a high-water absorption rate of 6-7% in rubber aggregate. The compressive strength of cubes reached up to 48.6 MPa, 32.4 MPa, and 37.5 MPa in Series 1, 2, and 3, respectively. Implementing 10% coarse and 10% fine rubber aggregate enhanced the compressive strength by 10.5%. There is clear evidence on improved mechanical properties of rubberized concrete with the addition of non-homogenous rubber aggregates.
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A comparative study to evaluate the effectiveness of different structural forms for medium-rise apartment buildings
(IEEE, 2022-07) Wijekoon, S; Jayasinghe, T; Herath, S; Herath, A; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
The rapid urban migration and the infrequency of spaces in megacities have become a challenge for all most all countries. To fulfill the housing requirements of the ever-growing population with the scarcity of valuable lands, the best solution is to come up with high-rise or medium-rise apartment buildings. Even though there are different structural forms that can be incorporated into high-rise apartment structures, most of the time structural designers select based on their experience and approach which are not effective all the time. The structural design for a given structure should be optimum in terms of structural performance and associated costs. Since wind and seismic forces govern the design of high-rise structures, those lateral forces are significant to be studied. So, this analytical study was carried out to evaluate the effectiveness of six different structural systems of 20-story RC (Reinforced Concrete) structures under the effect of wind and seismic loadings including a moment-resisting frame as the base model, four wall frame structures and a frame-tube structure. Models are compared based on the parameters such as maximum top storey displacement, inter-storey drift ratios, member forces and moments utilization, seismic induced base shear and human perception levels of lateral acceleration.
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Study on concrete-filled double-skin circular steel tubes under axial compression
(IEEE, 2022-07) Vitharana, TVDVK; Baskaran, K; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
In this research, an attempt has been made to evaluate the performance of concrete-filled double-skin circular steel tubes (CFDSCT) under axial compression and their application in buildings in terms of performance. Concrete-filled double-skin steel tube (CFDST) is a composite construction component. It consists of two steel layers with concrete sandwiched in between the tubes. The inner hollow steel section acts as formwork and reinforcement for the concrete. CFDST has numerous advantages, which include high strength, high bending stiffness, and good seismic and fire performance. Moreover, this type of structural member is not being used largely in construction, hence it’s vital to investigate and obtain a clear analysis of the implementations. This study presents a detailed investigation of how CFDSCT columns behave under axial compression, by experimenting and further verifying it through analysis of the structural component by developing a numerical model using “ABAQUS” finite element software. The experimental results were further compared to theoretical calculations performed using the “Eurocode 4” design standard. The simulation and the theoretical data are in good compliance with the test results. Ultimately, using a numerical model developed with SAP2000 software, this study discusses the feasibility of using CFDST columns in buildings in seismic performance.
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Framework for sustainable management and utilisation of wetland resources: a case study of the Madinnagoda marsh
(IEEE, 2022-07) Pathirana, H; Manatunge, J; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Wetlands, the lands of areas saturated with water throughout the year or seasonally, are the vital ecosystems of the earth. Madinnagoda marsh (wetland), in the suburbs of Colombo, is one such valued ecosystem embracing the sad truth of wetland degradation that has occurred persistently during the past few decades. Therefore, this study was carried out to develop a framework focusing on the sustainable management and utilisation of wetland resources at Madinnagoda marsh. The DPSIR (Drivers–Pressures–State changes–Impacts-Responses) framework was used for the study, an excellent tool for analysing environmental issues and devising sustainable solutions. This study attempts to further develop this Framework and then test it by applying it to Madinnagoda marsh as a case study. The usefulness of the Framework in appraising strategies to sustainably manage and utilise the wetland resources was measured as per the level to which its strategies fulfil the 17 Sustainable Development Goals (SDGs). Since there is no ongoing development plan for Madinnagoda marsh targeting its sustainable development, this research study leaves the validation phase as a future work - though a hypothetical situation is proposed to ensure that the validity of the Framework that has been proposed is well demonstrated.

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