Browsing by Author "Mallikarachchi, C"

Now showing 1 - 20 of 103

item: Conference-Full-text
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.
item: Conference-Full-text
3d full-field deformation measuring technique using digital image correlation
(IEEE, 2020-07) Nadarajah, S; Arulkumar, V; Mallikarachchi, C; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
Full-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-Abstract
Adoption of precast hollow core panels for external walls of multi-storey buildings
(Department of Civil Engineering, Faculty of Engineering, University of Moratuwa, 2022-12) Subakaran, R; Jayasinghe, MTR; Herath, HMST; Mallikarachchi, C
Precast hollow core wall panels have gained popularity for their efficient use as load-bearing and non-load-bearing wall elements. ICC ACOTEC hollow core wall panels are manufactured locally and intended to be used as internal partition wall panels in multi-storey buildings. Partition walls in general are not load-bearing elements, thus they do not undergo significant deformations. This research study focuses on verifying the usability of such precast panels as external wall panels in multi-story buildings, where their load resistance is investigated under lateral wind loads and vertical deformations due to column shortening effects. In addition, using the shape optimisation technique in-built into ABAQUS/CAE advanced finite element software and parametric optimisation study, a better layout for the precast wall is also proposed and its performance is compared with the current standard layout under similar loading and boundary conditions. The numerical model was validated using experimental test results and the optimised panel has a 16% lower net volume than the original hollow panel. Meanwhile, the optimised panel did not show any reduction in strength properties and does not pose any challenges in manufacturing. Using shape-optimised panel sections, panel assemblies are simulated to investigate the panel assembly response under wind loads. Further, recommendations are given on the maximum number of wall panels that could be installed as a single assembly under different wind load intensities at various heights of multi-story buildings. Considering practical aspects, these recommendations are integrated with proposals on connection mechanisms between panel assemblies. Due to the nature of the scope of this research study, long-term effects such as creep and fatigue were not incorporated, and it is recommended to conduct experimental tests for the proposed panel assemblies before practical usage.
item: Article-Full-text
AI-powered smart recycling: turning plastic trash into treasure
(University of Moratuwa, 2023) Kristombu, S; Thilakarathne, BS; Perera, S; Mendis, P; Ruwanpathirana, G; Rohanawansha, H; Wijesinghe, N; Mallikarachchi, C; Weerasinghe, P; Herath, S
In a world grappling with environmental challenges posed by plastic waste, innovative solutions are emerging to address the pressing issue of plastic recycling. Among these solutions, Smart AI-enabled automation and Upcycling stand out as promising technologies that offer the potential to revolutionize the way we handle and repurpose plastics. These technologies harness the power of artificial intelligence (AI) and automation to streamline the recycling process and transform discarded plastic materials into valuable products.
item: Conference-Abstract
Analysing the non-linear bending behaviour of ultra-thin woven composites at high curvatures
(Department of Civil Engineering, 2023-09-27) Tennakoon, TMH; Mallikarachchi, HMYC; Mallikarachchi, C; Hettiarachchi, P; Herath, S; Fernando, L
Deep space missions require self-deployable structures built of ultra-thin materials which can be carried to space in a limited space. Therefore, a growing demand for ultra-thin woven composites has been identified in space engineering applications. Understanding their mechanical behaviour is crucial for the effective optimisation of future structures because they experience extreme curvatures when in use in both folding and deploying mechanisms. It is more challenging to predict the overall mechanical behaviour of these composites due to their complicated geometry and nonlinear behaviour of its constituent parts. A common method to solve this problem is multiscale modelling, in which the system is simultaneously described by multiple models at varying scales. Micromechanical, mesomechanical and macromechanical scales are taken into consideration for woven fibre composites. Physical experiments revealed that ultra-thin woven fibre composites show a significant drop in bending stiffness at higher curvatures. The first objective of the study focuses on checking whether there is a thickness reduction of the plies at high curvatures which can be a possible reason for the reduced bending stiffness at high curvatures. As the second objective, it is expected to introduce air voids in resin to capture the non-linear bending response of woven fibre composites observed under high curvatures. Due to the deformation of the fibres and the weave structure at higher curvatures, woven fibre composites may exhibit variations in thickness. Resin matrices usually have lower stiffness compared to the reinforcing fibres. As a result, when the composite is subjected to higher curvatures, the fibres on the inner side of the curve may experience compression, leading to a reduction in thickness, while the resin matrix tends to flow and redistribute in response to the applied forces. The flow of resin can have both positive and negative effects on the thickness variation. On one hand, the ability of the resin to flow and redistribute can help accommodate the compression of the fibres and reduce the overall thickness reduction. According to the obtained results from the Dry Fibre model and the Resin model, except for the mid-section of the Dry Fibre model, there is no significant thickness variation at other locations compared to the original thickness in both the Resin model and Dry Fibre model. Although there is a thickness reduction at the mid-section of the dry fibre model, at high curvatures thickness starts to increase again which is against the experimentally observed bending behaviour. So, according to the obtained thickness variation results from the two models, there is no clear connection between bending stiffness reduction and thickness variation. To check the effect because of voids, Fibre Volume Fraction of the composite was used. The Fibre Volume Fraction is defined as the ratio of the volume of fibres present to the total volume of the layer. From the second objective, it was observed that there is a 6-8 % reduction in longitudinal stiffness, transverse stiffness, and shear stiffness with the void ratio. Variation in the Poisson’s ratio with the void ratio is low compared to other mechanical properties.
item: Conference-Abstract
Analysis of curved crease origami structures
(Department of Civil Engineering, 2023-09-27) Kuruppu, KALH; Mallikarachchi, HMYC; Mallikarachchi, C; Hettiarachchi, P; Herath, S; Fernando, L
Research on origami-based folding patterns has led to major technical developments from nanoscale metamaterial to large-scale deployable space structures. Deployable space structures such as solar sails and reflectors require them to be stored in a small volume while being able to deploy into a large configuration when in operation. The developability of origami facilitates the employment of deployability and self-actuation qualities in making these lightweight structures. In general, these structures are constructed with ultrathin materials and the quality of deployed surface increases the efficiency of the functionality of the structure. The curved crease origami structures consist of fewer creases than their equivalent straight crease counterparts. Lower number of creases leads to increase in efficiency as well as faster manufacturing rate. At present origami related research is mainly focused on predicting straight crease behaviour and the possible use of curved crease origami folding patterns requires more attention. This research is focused on studying the effect of membrane thickness on the folding behaviour of the curved-crease Miura Ori structures. Analytical equations for predicting the edge curve motion were first considered after a thorough literature review and an elliptical curved-crease Miura structure with a radii 40 mm and 69 mm made of 80 gsm copier paper was selected as a case study. The proposed numerical scheme for predicting folding and deployment behaviour discretises the curved crease into a series of straight line segments which are then replaced with a series of rotational springs. The equivalent rotational stiffness of a perforated straight crease was measured using a simple experimental setup which measures the force required to open a crease with crease angle opening. Same procedure was repeated for three different specimens and the mean rotational stiffness was used as an input to the rotational spring employed in the numerical model. The selected curved crease pattern was then simulated using the proposed numerical technique to obtain the deformed configuration under predefined loading conditions. The predicted shape was then validated against surface mesh obtained using a LiDAR scan of a physically constructed model under similar loading conditions. The experimentally validated numerical technique was then used to assess the changes in folding behaviour with changing membrane thicknesses. It is shown that the membrane thickness has a clear impact on the folding of the curved crease Miura Ori structure. Change in edge curve location leads to an overall change in displacement of the folded structure and hence the overall deployability of the structure changes with varying membrane thickness. This change of the edge curve coordinates gets accumulated when the base structure is tessellated to form the final deployable structure.
item: Conference-Abstract
Analysis of optimal expansion level of a single runway airport
(Department of Civil Engineering, Faculty of Engineering, University of Moratuwa, 2022-12) Siriwardena, KDSV; Perera, HLK; Mallikarachchi, C
Air travel is rapidly increasing all over the world and airport capacities are crucial when serving this growing demand. When it comes to airport capacities, whether it is passenger or freight, runway capacity is the key determining factor among many. At the same time, adding a runway to an existing airport is an expensive process from the design itself to obtaining approvals, construction and completion, compared to any other developments associated with an airport such as passenger areas and other service areas. However, despite the cost and other negative external factors involved, most airport authorities tend to make a bold decision to add another runway to the existing airport without looking at optimising existing and future operations. This seems to be the case for the Bandaranaike International Airport (BIA) which made plans to add a second new runway to accommodate future traffic. Therefore, the main aim of this research is to identify how to achieve the optimal expansion of a single-runway airport without adding a second runway. This is achieved by identifying critical parameters that affect the runway capacity and analysing ways to obtain the optimal capacity. Hence, the next appropriate solution to accommodate future traffic growth is to optimise current operations rather than physical expansion, due to drawbacks such as high capital costs, long implementation times, community opposition, and so on. After collecting the necessary data, an analysis was carried out to determine the current capacity and the utilisation of the runway in BIA. From the analysis, it was found that during a peak period more than 50% of the runway capacity is idling, meaning that it is been underutilised heavily at present. In other words, BIA can simply double the operations with the existing runway and now the question is whether BIA expects a growth more than this within the next 15-20 years. Beyond finding out the truly available runaway capacity there are ways to optimise runaway capacities. One such option would be to assist air crafts to evacuate from the runaway in the shortest possible time so that they can conduct the next operations. This was found to be the next largest bottleneck hindering runaway capacity and as a result implementation of highspeed exits have been considered in this study using the REDIM software. In addition, the best departure and arrival sequences were discovered using Python code to utilise the time more efficiently as Runway Occupancy Time (ROT) differs according to the aircraft category. It canbe concluded that the existing runway capacity can be further improved by optimising the current operations, as ROT was reduced by 10%.
item: Conference-Abstract
Analysis of the effect of wind on façade fire propagation through computational fluid dynamics modelling
(Department of Civil Engineering, Faculty of Engineering, University of Moratuwa, 2022-12) Gunarathne, GKUS; Rathnayaka, S; Weerasinghe, TGPL; Nanayakkara, SMA; Mallikarachchi, C
Façade fires are one of the most critical and increasingly frequent hazards in buildings. These fires pose a great risk to the building occupants. The Grenfell Tower fire, which happened in 2017, killing 72 people, is one of the deadliest façade fire incidents. Events like these emphasize the importance of studying the nature of façade fires. Façade fires can spread quickly through the full height of the building. Also, these fires can spread into nearby structures. Researchers have identified several factors that affect façade fire propagation. The main factors include façade material, cavities, geometry of the building, and wind. The focus of this study is the effect of wind on façade fire propagation. Building standards have set requirements to ensure the fire safety of façades. A large-scale façade fire test is one of the methods that building standards have used for this purpose. There are several large-scale façade fire test types in different countries, and the nature of these tests varies significantly from one another. One common theme in all those tests is that they do not consider the effect of wind. Therefore, even though the façades are designed according to the building standards, there is an unforeseen risk in fire situations when the wind is present. This study tries to address that limitation by numerically modelling a large-scale façade fire test and assessing the effect of wind. Fire Dynamic Simulator (FDS) was selected as the numerical tool. FDS is a Computational Fluid Dynamics (CFD) software for fire-driven fluid flows. First, a validation study was performed by numerically modelling a large-scale façade fire test that was conducted in a fire test facility in Melbourne. The experimental setup was 18 m tall, and thermocouples were placed at 10.5 m, 13.5 m and 16.5 m heights to record the temperatures. Wind speed and direction were measured at a height of 10 m. The test specimen consisted of two façade materials: an aluminium composite panel (ACP) with a combustible polyethylene core and a completely non-combustible profiled aluminium panel. The ACP panels consisted of a 4 mm polyethylene core sandwiched in between two 1 mm thick aluminium sheets. These materials were simulated in the numerical model using the material properties gathered from literature and product-specific data sheets. The total dimensions of the numerical domain were 22.4 m x 20.8 m x 19.2 m (length x width x height). This domain was large enough to account for the whole test, the fire plume resulting from the combustion, and the turbulences due to wind. Monin-Obukhov similarity theory was used to model the wind inside the numerical domain. The thermocouple results were extracted from the numerical model, and they were validated using the experimental results. The flame behaviour of the numerical model was compared with that of the experiment for further validation. After the validation, the effect of wind was examined through further numerical modelling. It has been shown that wind has a significant impact on façade fire propagation. The façade fire spread decreases with increasing wind speed when the wind direction is parallel to the main wall of the test specimen. Wind direction also impacts fire propagation. Findings from this study highlight the importance of considering wind in façade fire safety, especially in large-scale façade fire tests.
item: Conference-Abstract
Analysis of the shear behavior of stabilised soil-concrete interface in geotechnical structures
(Department of Civil Engineering, 2023-09-27) Wijesingha, WAW; Sampath, KHSM; Mallikarachchi, C; Hettiarachchi, P; Herath, S; Fernando, L
Understanding the behaviour between the interface of soil and concrete structures has a significant role when considering stability and the capacity of geotechnical structures such as shallow foundations, deep foundations, and earth-retaining structures. Quarry dust (QD) is an alternative waste material used for soil stabilisation to improve the engineering properties of existing weak soil, such as bearing capacity, stability, strength, and compressibility. Assessing the respective behaviour of the interface under various mix proportions of QD and the existing soil is important since the geotechnical properties of stabilised soil mainly vary with the mix proportion. This research investigates the influence of different QD and clayey sand (SC) mix proportions on the interface shear behaviour by laboratory experiments with modified direct shear tests. The effectiveness of the clayey sand stabilisation process using QD is demonstrated based on the plasticity characteristics, compaction characteristics, and shear strength of the soil-soil interface and the soil-concrete interface. The results demonstrate that QD provides effective clayey sand stabilisation since the Plasticity Index is decreased by 46.8%, MDD is increased by 11.26%, and Shear Strength is increased by 74.57% under 200 kN/m2 of normal stress when the QD percentage in the stabilised soil is increased from 0% to 20%. Also, 40% of QD was obtained as the optimum mix proportion to stabilise clayey sand based on compaction characteristics since MDD is increased up to 40% and again decreased with the addition of QD. This investigation demonstrates that QD provides highly effective shear strength increment to clayey sand, and the shear strength is completely governed by the effect of friction angle beyond 10% QD addition since the cohesion is negligible. Further, in the second phase, the accuracy of recommended co-relations between interface shear strength properties and soil shear strength properties provided in existing design codes has been assessed, particularly focusing on the QD-based stabilised clayey sand and using two concrete surfaces that have different roughness values (R1 and R2). The results demonstrate that when 20% of QD is added, the Interface Friction is increased by 23.2% in the soil-concrete interface (R1) and 22.5% in the soil-concrete interface (R2), and the obtained Interface Friction Angle Reduction Factors (IFARF) are in the range of 0.72 – 0.95. Therefore, the experimental results concluded that the IFARF, used in current design practices and values recommended in design guidelines, overestimates the interface shear reduction of the SC soil when it is stabilised with QD. In contrast, the Cohesion Reduction Factor (CRF), used in the current design guidelines, underestimates the interface shear reduction of clayey sand and stabilised clayey sand with QD when the contacted concrete surface is smoother than the relative roughness of 0.510 since the obtained CRFs are in the range of 0.52-0.67. Hence, the outcomes of the research conclude that the interface shear behaviour highly varies with the interface soil properties and the surface roughness of the structure; as such, adopting a common interface reduction factor for both friction angle and cohesion is not always accurate for designing geotechnical structures. It is recommended that a design optimisation should be performed by carrying out appropriate interface shear strength tests, considering the soil types and concrete surface properties, especially when the existing soil is stabilised with an additive like QD.
item: Conference-Abstract
Applicability of calcium carbide residue for soil stabilization: a systematic review and a meta-analysis
(Department of Civil Engineering, Faculty of Engineering, University of Moratuwa, 2022-12) Sandamali, DMTU; Sampath, KHSM; Mallikarachchi, C
The use of Calcium Carbide Residue (CCR) which is a calcium-rich material as a soil stabilizer is often discussed as a solution to reduce negative environmental impacts and costs involved with soil stabilization with cement. By mixing an optimum CCR content with soil, a significant improvement can be achieved in soil properties. In terms of compaction properties, the addition of CCR decreases the maximum dry density (MDD) of soils while increasing the optimum moisture content (OMC). A significant increment of unconfined compressive strength (UCS) is observed with the increment of CCR dosage. However, the UCS of stabilized soils tends to decrease with further addition of CCR once the optimum CCR content is reached. In addition, the plasticity index (PI) of natural soils decreases with the addition of CCR and becomes constant after the optimum CCR content is reached. This particular research studies the applicability of CCR as a soil stabilizer with a comprehensive literature review and several statistical models and correlations were developed to be used in the pre-feasibility stage of applying CCR as a soil stabilizer. Prediction models were trained and validated by analyzing the data collected from similar studies using the statistical tools available in Excel and MATLAB software. This study describes a multivariate linear regression model and a multivariate polynomial regression model which can predict the MDD, and OMC of soils stabilized with CCR, respectively within a prediction accuracy of ±5% using the compaction properties of natural soil and CCR mix proportion. Also, an artificial neural network (ANN) model with a R2 value of 0.99958 and an accuracy range of ±16% was developed to predict the UCS of CCR-stabilized soil after a curing period of 28 days. In addition to that, a gaussian process regression (GPR) model was introduced to predict the plasticity index (PI) of CCR stabilized soil with a R2 value of 0.98 and a predictive accuracy of ±3%. This model can also be used to estimate the optimum CCR content.
item: Conference-Abstract
Applicability of rcpt for performance-based durability design of reinforced concrete structures
(Department of Civil Engineering, 2023-09-27) Abeywickrama, HM; Nanayakkara, SMA; Mallikarachchi, C; Hettiarachchi, P; Herath, S; Fernando, L
Concrete is an extensively used composite material in the construction industry, known for its heterogeneous nature. In the context of structural service life predictions, the durability of concrete plays a vital role, especially with the advancement of new constituent materials. Among various factors contributing to concrete deterioration, corrosion of reinforcement poses a significant challenge to durability. Chloride ingress is one of the primary factors that cause corrosion of reinforcements. Therefore, this research paper focuses mainly on the impact of chloride-induced corrosion which is the major cause of corrosion of reinforcement. There are several tests that are still available to evaluate that kind of corrosion. The Rapid Chloride Penetration Test (RCPT) serves as a quick measure of chloride ion penetration resistance, which relies on the characteristics of pore structure and pore solution. The standard RCPT (ASTM C1202) is done under certain conditions. But there are limitations and drawbacks of RCPT due to certain conditions. In that way, the significant effect of RCPT results can be evaluated by changing the voltage, cathodic solution, and time. Therefore, this study investigates the influence of the cathodic solution changing with natural seawater to represent more actual conditions. The chloride content of that seawater was 10% w/w. The standard RCPT gave 2401 C while the modified method gave 3122 C as the charge pass. Once the RCPT procedure concludes, concrete powder samples were collected at various depths to determine the chloride profile. These obtained profiles were then subjected to nonlinear regression analysis to calculate chloride penetration depths. By applying Fick's second law to the chloride profile and penetration depth, the chloride diffusion coefficient was determined. Finally, a performance-based design approach was proposed, linking RCPT values with the Fib Model Code 2010, to predict the service life of uncracked concrete affected by corrosion. Then results were compared with the results which were obtained by a standard method for chloride diffusion coefficient. That standard method used for this study was RCMT (according to NT BUILD 492). Then the obtained diffusion coefficient values were 21.43 mm2/year, 20.97 mm2/year, and 21.02 mm2/year for the standard RCPT, the modified method and the RCMT, respectively. The errors were 0.2% and 1.9%, for the modified method and standard RCPT when compared with RCMT result. On the other hand, the predicted service lives for standard RCPT and modified methods were 44.32 years and 42.84 years, respectively. The RCMT gave the service life as 40 years. So, the percentage in errors were 10.8% and 7.1% for standard RCPT and modified methods when compared with RCMT result. In conclusion, standard RCPT should be modified by using sea water from actual environment instead of 3% NaCI solution if the structure is contact with sea water. RCPT can be used for performancebased durability designs. However, further investigations are required to establish the correlation between RCPT values and chloride diffusion coefficient for different grades of concrete.
item: Conference-Abstract
Applicability of standard density in quality control and quality acceptance of asphalt surfacing
(Department of Civil Engineering, Faculty of Engineering, University of Moratuwa, 2022-12) Rathnasiri, KAPS; Mamperachchi, WK; Mallikarachchi, C
Proper compaction plays a vital role in maintaining the quality of asphalt pavement works. As a quality control (QC) and quality acceptance (QA) parameter, the degree of compaction expressed as a percentage ratio between field density and the reference density is employed in the pavement industry. Currently, Marshall density, maximum density and control strip density are used to establish the reference density and formulate the degree of compaction. However, for decades, Marshall laboratory density has been the mainstream practice to specify the reference density in Sri Lanka. This study focuses on developing a systematic approach called the "Standard density method" to establish the reference density. The standard density is determined as the mean value of densities of Marshall test specimens from morning and evening operations for a specified number of days after the commencement of construction. The experiments were designed to evaluate the feasibility of the concept of standard density by comparing current practices with the proposed method. Field core density and Marshall laboratory density measurements were collected from various road projects, and compaction performances were evaluated. A graphical comparison, a statistical test method (t -test) and validation tests were conducted to analyze the compaction performance and acceptance of the proposed method. The findings showed that standard reference density could be used as the most effective QC / QA testing parameter for roads that use the same asphalt mixture design, batching plant, laying and compaction procedures. Moreover, statistics revealed a significant relationship between the level of compaction results in both current and proposed methods in major projects. Furthermore, the results showed that the standard density method is very sensitive to the variations in asphalt manufacturing, placing, laying and compaction procedures.
item: Conference-Abstract
Assessing the readiness for digital technologies adoption for enhancing productivity in the Sri Lankan construction industry
(Department of Civil Engineering, 2023-09-27) Chathuranga, IHN; Siriwardana, CSA; Mallikarachchi, C; Hettiarachchi, P; Herath, S; Fernando, L
The Construction Industry (CI) is a vital sector that continually seeks to enhance productivity and profitability, facing distinct challenges compared to other industries. Amidst global trends emphasising the integration of digital technologies for improved productivity, the CI's adoption of such innovation technologies lags in a global perspective. The study recognises that digital transformation is vital to significant productivity gains in the construction industry. However, in the Sri Lankan context, a comprehensive study has not yet been done to develop a tool to assess the Sri Lankan construction industry's readiness towards digitalisation. This research paper addresses this gap by developing a readiness model and a self-assessment tool to measure the organisational readiness of Sri Lankan construction industry to adopt digital technologies in a holistic approach. This study employs a multi-dimensional approach by amalgamating the Technology-Organisation-Environment framework and the Readiness for Workforce Strategic Change Management framework, effectively addressing the complexities of digital technology adoption within organisations. A rigorous literature survey identified 15 readiness indicators spanning Environment, Technology, Organisation, Leadership, and Workforce dimensions to evaluate the construction industry's readiness. The research employs a mixed-methods approach involving a literature survey, pilot questionnaire, comprehensive questionnaire, and robust data analysis techniques, including descriptive, factor, and Fuzzy Synthetic Evaluation analyses. The outcomes reveal a nuanced understanding of critical indicators, categorised into two groups named ELPA (Environment, Leadership, Workforce Attitude, and Organisational Performance) and TOK (Technology, Organisation, and Technical Knowledge). The study's primary contributions include the development of an organisational readiness model and a selfassessment tool, facilitating self-evaluation by construction organisations. The developed readiness model integrates these dimensions through weighted indicators, providing a holistic assessment of readiness. The self-assessment tool operationalises the model, enabling practitioners to gauge readiness by assessing each indicator's relevance towards digitalisation. The model is underpinned by Fuzzy Synthetic Evaluation, ensuring objectivity and addressing subjective judgments. The assessment tool is precious for its practical applicability, offering a user-friendly approach for organisations to identify their strengths and weaknesses towards digital technology adoption at the organisational level. Ultimately, this research sheds light on the readiness landscape of the Sri Lankan construction industry, paving the way for strategic interventions and informed decision-making towards digitalisation. By aligning strategic plans based on the results obtained from the developed readiness model, organisations can drive their digital transformation journey, harnessing the potential of digital technologies to boost construction industry performance, bridge productivity gaps, and contribute to the economic growth of Sri Lanka.
item: Conference-Abstract
Assessment of traditional water yield forecasting methods based on selected two dry zone basins in Sri Lanka
(Department of Civil Engineering, Faculty of Engineering, University of Moratuwa, 2022-12) Madusanka, WDP; Rajapakse, RLHL; Mallikarachchi, C
The majority of dry zone basins are still ungauged in Sri Lanka, and this has led to uncertainties in the planning and development of water management infrastructure. The Irrigation Guideline of Sri Lanka (IGM) has been widely in use to estimate the basin yield, but even so, there is insufficient evidence to evaluate the accuracy of the estimations under the changing climate conditions. Therefore a need exists for the comparison of available water yield models to close this gap and provide accurate yield estimations. In the current study, the observed streamflow yield data from Kirindi Oya and Maduru Oya basins were used to compare the yield estimates derived from the IGM and HEC-HMS models. Daily and 75% probable rainfall data were considered as the input data for the models and the model results were compared with the observed streamflow data. The evaluation has been carried out by considering the flow hydrographs, annual cumulative error, flow duration curves, runoff coefficients, and the Mean Ratio of Absolute Error (MRAE) value as an indicator. The two dry zone basins Thanamalwila and Padiyathalawa were considered for the study. The periods of comparison of the Thanamalwila and Padiyathalawa watersheds were from 2000-2015 and 2007-2015, respectively. Cumulative water yield error between observed and simulated yield, flow duration curves, and runoff coefficients were the critical elements used to compare simulation results with observations. Comparisons in the two selected basins show that the IGM is still the better model for estimating yield in watersheds in the dry zone, and it was found that rainfall is the dominant factor influencing yield. The comparison of the two models by using the 75% probable rainfall data as indicated in the IGM (Analysis 1) as the input data showed that it is the closest monthly yield evaluation model compared to observed data in the Padiyathalawa and Thanamalwila watersheds and annual differences in estimations were 47.9% and 39.8%, respectively. The HEC-HMS model results ended up with 83.9% and 83.8% annual differences for Padiyathalawa and Thanamalwila watersheds, respectively. In the comparison of the two models by using the actual rainfall data collected from the selected gauging stations (Analysis 2), for the Padiyathalawa watershed, HEC-HMS gives the closest monthly yield estimation with a 34.18% annual streamflow overestimation error. For the Thanamalwila watershed, the IGM model gives the closest monthly yield estimation, and the annual error was 32.2%. The HEC-HMS model gives overestimated values in the Padiyathalawa watershed in Analysis 2 while producing underestimated values in other cases. The IGM produces underestimated values for all cases. Due to the ambiguous variation of HECHMS yield results in each watershed in the same zone, it is recommended that the IGM model be used for yield estimations in the dry zone basins with similar characteristics.
item: Conference-Abstract
Assessment of tsunami hazards and exposure of sri lanka: case study in south-western coast
(Department of Civil Engineering, 2023-09-27) Kanishka, UAM; Ratnasooriya, AHR; Mallikarachchi, C; Hettiarachchi, P; Herath, S; Fernando, L
This research focuses on assessing the exposure of Sri Lanka's southwestern coast to tsunami hazards. Tsunamis are a series of ocean waves triggered by impulsive disturbances, such as undersea earthquakes, volcanic eruptions, landslides, and cosmic explosions. The catastrophic impact of tsunamis, as demonstrated by the devastating Indian Ocean tsunami (IOT) event in December 2004, underscores the urgent need for an effective early warning system to mitigate the loss of life and property in coastal regions. The study specifically examines the vulnerability and exposure of the southern coastline ranging from Rathgama to Dadalla. The Community Model Interface for Tsunami (ComMIT) is used in the research's numerical simulation. Access to a precomputed tsunami scenario database and the MOST (Method of Splitting Tsunami) model created by the NCTR (National Center for Tsunami Research) is made possible through ComMIT, a user-friendly graphical interface. The model simulates tsunami waves with magnitudes ranging from 7.6 to 9.2 Mw, originating from selected unit sources along the Sunda trench in Indonesia and the Makran fault in Pakistan. The Sunda Arc is a volcanic arc that formed the islands of Java and Sumatra. Makran fault is located to the northwest off the coast of Pakistan. Makran trench is less affected relative to Sunda arc. For this research study five zones in Sunda trench and one zone in Makran fault are taken for segmentation of unit sources. By combining the model's output with Green's law, the research calculates the maximum wave heights at a depth of 1 m. This data is crucial in identifying the levels of tsunami exposure along the coastal stretch. Furthermore, it enables the accurate projection of the exposure, facilitating the incorporation of lag-time effectively into early warning systems. The findings of this study will contribute to enhancing the understanding of tsunami hazards in Sri Lanka and specifically the southwestern coastal region. Exposure assessment will aid in issuing timely and accurate warnings, minimising the potential for fatalities and injuries in future tsunami events. Ultimately, the research aims to improve disaster preparedness and enhance the resilience of coastal communities in Sri Lanka to mitigate the impacts of tsunamis.
item: Conference-Full-text
Characterising the Self-opening Behaviour of Single Creased Kapton Polyimide Films
(IEEE, 2021-07) Navaratnarajah, S; Piyumi, C; Mallikarachchi, C; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Use of thin folded membranes for deployable structures are becoming increasingly popular especially in aerospace applications such as a deployable solar array, sun shields, and solar sails. The folding and compaction process of thin membranes, which introduces permanent, nonrecoverable, localized plastic deformation, changes the geometric shape and material properties. The underlying mechanics in the deployment of creased membrane structures are self-opening and then forced-opening beyond a stable stress-free state. The focus of the previous studies was limited to the characterisation of crease behaviour during force opening. This paper presents an experimental study to characterise the crease mechanics of a single creased membrane during self-opening behaviour which is crucial in the design of gossamer structures. A simple analytical study was performed to predict the moment-rotation response of the crease and hence shows a good qualitative agreement with physical experiment results. It is shown that the moment-rotation response of a single crease can be idealized to a linear rotational spring in virtual simulation and the spring stiffness depends on the thickness of the membrane.
item: Conference-Abstract
Cost economics of precast walling systems for multistorey buildings – a case study-based approach
(Department of Civil Engineering, Faculty of Engineering, University of Moratuwa, 2022-12) Rathnayake, RMBCK; Jayasinghe, C; Mallikarachchi, C
Traditional monolithic building construction is labour and time- intensive and usually found in inadequate quality. Rapid urbanization and steadily expanding metropolitan populations need fast and time-saving construction technology, which can be aided using precast construction techniques. Precast construction offers numerous benefits including reduced construction time, minimal labour requirement, less resource wastage and higher quality. Despite the advantages of precast construction technology, Sri Lankan multi-storey building construction still predominantly relies on conventional on-site construction techniques due to a lack of fresh knowledge and less awareness about the benefits. Hence, this study aims to assess the cost- effectiveness and environmental impact of adopting precast concrete walling systems in multi- storey building construction in the Sri Lankan context through a life cycle thinking approach. This paper compares a precast concrete walling system with a conventional Cement Sand Block (CSB) walling system in terms of Life Cycle Cost (LCC) and Life Cycle Assessment (LCA). It evaluates the total impact using Eco-Efficiency Analysis. A case studybased approach was adopted and the LCC was compared using the Net Present Value (NPV) method. The results show that the CSB walling system is more cost-effective than the precast concrete walling system in the long run in the Sri Lankan context. But the Ecoefficiency Index of both walling materials is in the same range according to the percentages they got. Moreover, precast walling system shows considerable time and labour saving with improved quality of construction. Therefore, the findings of this study help to select a walling material for multi-storey building construction from a broader perspective.
item: Conference-Abstract
Critical evaluation of available predictive model for root permeated soil strength using numerical modeling
(Department of Civil Engineering, 2023-09-27) Wellage, SG; Pallewatta, M; Mallikarachchi, C; Hettiarachchi, P; Herath, S; Fernando, L
Soil bioengineering combines plants' root systems to prevent erosion and stabilise slopes, offering sustainable, nature-based solutions for environmental restoration. Shear strength evaluation of soil bioengineering is discussed under mechanical and hydrological aspects but remains unimproved, highlighting a significant research gap. This research presents a comprehensive investigation on the shear strength improvement of soil through soil reinforcement, focusing on the use of vegetation roots as a reinforcement material. The study combines experimental testing and numerical modelling using Abaqus software to assess the effectiveness of root reinforcement in enhancing soil stability. The experimental phase involved conducting tensile strength tests on natural Alstonia Macrophylla roots. Performing large-scale direct shear tests with roots can be a challenging endeavour. Roots have a significant impact on the mechanical behaviour of soil and introduce complexities into the testing process. In this research, Finite Element Analysis (FEA) was implemented in Abaqus to model large-scale direct shear tests involving soils with roots. This approach offered a versatile and powerful means to simulate the complex interplay between roots and soil behaviour. Obtained experimental data, including the Young's modulus value of the root, were utilized for the numerical model calibration. In the experimental phase of the study, a practical approach to quantify the tensile strength of roots was employed. This was achieved using a Universal Testing Machine (UTM), a widely used apparatus for measuring the mechanical properties of materials. However, certain properties such as Poisson's ratio and density for the root were obtained from relevant literature due to the unavailability of specific data. For validation purposes recently conducted direct shear tests results on Alstonia Macrophylla root permeated soil were adopted. The numerical model was established using a solid model approach, simulating the actual size of the soil samples, and employing appropriate material properties. The simulation accounted for soil-soil and soil-root contacts using appropriate contact models. In simulating the direct shear test, a "Surface-to-Surface contact" approach modelled soil and root interactions. Soil surfaces were defined as "Master" and "Slave," using a "Penalty formula" for tangential friction and a "hard" contact type for normal behaviour. Roots were treated as embedded bodies with ABAQUS constraints, ensuring realistic contact representation. The results of the numerical simulation demonstrated the stress concentration within the soil, particularly in regions in contact with the root, indicating significant shear strength improvement due to root reinforcement. The obtained shear stress-displacement relationship allowed for the determination of the shear strength of the system. Simulation and experiments showed root-soil shear strength enhancement. Accurate parameters and 3D modelling were vital for reliability. This study's findings provide guidance for root growth regulation and slope protection research. Overall, this research contributes to the understanding of soil reinforcement mechanisms and provides valuable insights into the use of Soil bio engineering as an effective means of enhancing soil stability.
item: Conference-Abstract
Critical evaluation of transport sector ndcs for a lowcarbon future
(Department of Civil Engineering, 2023-09-27) Aponsu, MKD; Bandara, JMSJ; Mallikarachchi, C; Hettiarachchi, P; Herath, S; Fernando, L
The Nationally Determined Contributions (NDCs) of the transport sector have been recognised as one of the most effective measures to reduce greenhouse gas (GHG) emissions. This study aims to conduct a comprehensive and critical evaluation of the NDCs of the transportation sector in Sri Lanka to assess their effectiveness in achieving a low-carbon future. The first set of NDCs was implemented by the Mahaweli Development and Environment Ministry in 2016 and was subsequently submitted to the United Nations Framework Convention on Climate Change. In July 2021, Sri Lanka updated its NDCs, reflecting its ongoing commitment to combating climate change. This research aims to identify the gaps and limitations of current policy and to plan strategies and recommend effective strategies to support the sector's transition to a sustainable future. Through evaluation of the effectiveness of current NDCs, we can provide information on the country's progress toward achieving its climate goals. This research can provide valuable recommendations to policymakers and stakeholders to overcome these challenges and promote sustainable development in the transport sector. To prioritise NDCs, a set of criteria was developed based on research objectives and the specific needs of the transportation sector. These criteria served as a framework for subsequent analysis. A questionnaire survey was administered to gather information from transportation industry professionals and the general public regarding NDCs. The collected data was analysed using suitable statistical approaches, using the Statistical Package for the Social Sciences (SPSS) software as a tool. A list of essential NDCs for the transport sector was established using the prioritised criteria and the feedback obtained from the questionnaire survey. This list served as the basis for the subsequent evaluation and analysis of the identified NDCs. Finally, conclusions were drawn based on the evaluation and analysis regarding the significance and impact of the prioritised NDCs in the transportation sector. This study's results have helped increase awareness of the complexity of emission assessments in the transportation industry and have provided helpful information for planning and policy-making related to sustainable transportation. This research can provide valuable recommendations to policymakers and stakeholders to overcome these challenges and promote sustainable development in the Sri Lankan transport sector. In conclusion, implementing the proposed enhancements for the selected NDCs is crucial to effectively align Sri Lanka with the goals of the Paris Agreement within the designated time frame. Sri Lanka is particularly vulnerable to the impacts of climate change, underscoring the urgency and importance of taking decisive action. It is imperative to prioritise and address the identified issues to mitigate risks, enhance resilience, and contribute to global efforts in combating climate change. By proactively addressing these challenges, Sri Lanka can create a sustainable and climate-resilient future.
item: Conference-Abstract
Damage assessment matrix for low-rise masonry houses
(Department of Civil Engineering, 2023-09-27) Wickramathilake, GGTD; Jayasinghe, C; Mallikarachchi, C; Hettiarachchi, P; Herath, S; Fernando, L
Low-rise buildings are susceptible to damage from factors like poor design or construction quality, inadequate supervision, improper drainage, problems due to the soil condition, and adverse climatic conditions. In certain areas where expansive soil is present, especially in floodplain areas, significantly threatens lightly loaded structures due to uplift pressures. The objectives of this study were to identify the factors for the damages in low-rise masonry buildings, the level of effect of those factors for the damages, and develop a matrix to assess the damages in low-rise masonry buildings as a case study based approach. This study was based on the damaged houses which are in Higurakgoda in the North Central province of Sri Lanka and constructed with commonly available materials. Field investigation, detailed review of the reports that had been prepared after the investigation done by the National Building Research Organisation in Sri Lanka, preparation of the database, and analysis of data using Microsoft Excel and Power BI is the procedure followed in this research. All those houses have been constructed in an area that is underlain by the Minneri Oya alluvial deposit layer Through the detailed analysis, poor construction quality and the expansiveness of the soil were identified as the major factors for damage in the houses in the case study. With the aid of literature, this study considered liquid limit, plasticity index, clay content, natural water content, and free swell index of soil as dominant parameters that describe the expansiveness of soil, as well as the quality of construction, foundation type, wall material, and floor material as the factors affecting risk due to the poor construction quality as satisfaction. After determining the level effect of each considered parameter using the Analytical Hierarchy Process and actual data from the houses in the case study, a matrix that enables the prediction of the risk level of lowrise masonry houses on expansive soil was developed by combining two matrices developed to predict soil expansiveness and the risk level due to poor construction quality. The study also categorises possible damages, proposing an equation to predict the probability of structural cracks occurring in the building and a rationale to predict critical and possible types of cracks based on the risk level of the low-rise masonry house that is predicted using the proposed matrix. Validation of the proposed matrix using actual data demonstrated their accuracy in predicting risk levels. Therefore, when the construction details of the house and soil properties are identified, the outcomes of this research can be used to predict the risk level of low-rise masonry houses, the tendency to get structural cracks, and possible types of cracks. So, these findings can help assess and mitigate potential damage to low-rise buildings in expansive soil areas, enabling better construction practices and risk management strategies.