CERS - 2024

Permanent URI for this collectionhttp://192.248.9.226/handle/123/22814

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item: Conference-Abstract
Application of load bearing cement hollow block walls for multi storey housing
(Department of Civil Engineering, University of Moratuwa, 2024) Wijayarathna, YADKH; Jayasinghe, MTR; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
The economic challenges facing Sri Lanka have highlighted the need for affordable housing solutions. This study investigates the viability of load-bearing hollow block walls within a hybrid construction system for multistory residential buildings, utilizing precast slab panels and concrete hollow blocks as lightweight construction materials. The study aims to redefine traditional construction practices and propose an economically viable approach. Structural analysis was conducted using the “Manual for the Design of Plain Masonry in Building Structures to Eurocode 6”, to evaluate the load-bearing capacity and structural integrity of the hybrid system across varying building heights (three to eight stories). Two alternative wall configurations were assessed: (1) walls supporting simply supported beams that carry slab panel loads, and (2) walls directly supporting slab panels. The concrete hollow blocks used are standardized at 200 mm x 190 mm x 390 mm with 47% voids, and the height of wall panel is 3 m with a thickness of 200 mm. The block density is 22 kN/mm², with the mortar strength being 4.0 N/mm². The study showed that the wall configuration of Alternative 2 requires less block strength while maintaining efficient load-bearing capacity compared to Alternative 1 for buildings up to eight stories. Additionally, the Alternative 2 configuration can be applied to buildings up to six stories without needing additional frame support. For buildings with up to three stories, both wall configurations were found to be feasible under the current allowable block strength of 8 N/mm². Moreover, the block strength requirements for buildings up to eight stories using Alternative 2 were determined to be within the achievable limits of current manufacturing practices. This study contributes to the growing body of knowledge aimed at enhancing sustainable construction practices in the region. It offers a practical pathway for structural engineers to meet the increasing demand for affordable housing in urban areas while promoting sustainability of the construction industry. Furthermore, the findings emphasize the potential of using precast slab panels and hollow blocks to enhance the efficiency and sustainability of housing projects. Further exploration of the application of this hybrid system in seismic conditions is recommended as additional reinforcement measures might be necessary to ensure safety and durability under seismic loads. Also, it is recommended that methods to improve the strength of hollow blocks be explored further, particularly for taller structures. Adopting this innovative approach could significantly contribute to meeting Sri Lanka's urgent demand for affordable housing while promoting sustainable construction practices.
item: Conference-Abstract
Assess the impact of internal curing in roller compacted concrete using roof tile waste as fine aggregates
(Department of Civil Engineering, University of Moratuwa, 2024) Dilsara, VGS; Jayantha, WRAN; Mampearachchi, WK; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
The construction industry is increasingly prioritizing sustainable and eco-friendly practices, resulting in a growing interest in utilizing waste materials in concrete production. As environmental concerns continue to grow, innovative solutions are becoming essential to reduce waste and promote sustainability. One promising approach involves incorporating waste materials into concrete as internal curing agents (ICAs) to address the challenges associated with proper concrete curing. Proper curing is essential for enhancing the durability and mechanical properties of concrete, but conventional curing methods often have limitations, especially in concrete with a low water/cement ratio. This has led to a significant focus on exploring alternative methods, with internal curing gaining considerable attention. The concept of internal curing involves utilizing materials based on the ability to absorb and release water within the concrete matrix. This facilitates a more consistent and extended curing process. This research intends to address a gap in sustainable construction practices by assessing the feasibility of using roof tile waste as an internal curing aggregate (ICA) to replace fine aggregates in roller-compacted concrete (RCC). The utilization of roof tile waste not only encourages recycling and reduces landfill waste but also leverages its water absorption and desorption properties to improve the curing process. The research involved a comprehensive series of laboratory experiments to assess the potential usage of roof tile waste as an ICA. Furthermore, the study evaluates the impact of roof tile waste on the mechanical properties of RCC, specifically focusing on compressive strength, tensile strength, and flexural strength. To achieve this, RCC samples were cast with varying percentages of roof tile aggregates (RTA) replacing fine aggregates: 5%, 10%, and 15%. Each sample was subjected to testing to assess its performance compared to externally cured conventional RCC and uncured conventional RCC. The findings from the experiments revealed that the incorporating of roof tile waste as an ICA significantly affects the mechanical properties of RCC. The optimal performance for internal curing with RTA occurs at a 10% replacement level, balancing the benefits of internal moisture retention and the mechanical integrity of the concrete. The research emphasizes that utilizing 10% RTA replacement can lead to significantly improved early-age properties, demonstrating an 18% increase in 3-day compressive strength compared to traditionally cured RCC. This advancement is advantageous for pavement construction as it facilitates quicker access to traffic and shortens construction schedules. However, the study also identified certain constraints. Even though the early compressive strength displayed substantial enhancement, the tensile and flexural strengths of RCC samples with RTA were lower than those of conventionally cured RCC. This indicates that while roof tile waste is effective in enhancing early age compressive strength, further optimization is needed to improve its impact on tensile and flexural properties.
item: Conference-Abstract
Assessing future low-flow variations in a dry zone river basin under changing climate conditions
(Department of Civil Engineering, University of Moratuwa, 2024) Tharuka, WMS; Gunawardhana, HGLN; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Climate change significantly alters the low-flow regimes of river basins worldwide and presents significant challenges to water-scarce regions, especially in dry regions. This current study investigates the impact of climate change on projected low-flow variations in the Maduru Oya River Basin in Sri Lanka, focusing on the reach to the Padiyathalawa stream-gauge station. The study utilizes a lumped hydrological modeling framework, which used the HEC-HMS rainfall-runoff model to simulate streamflow behavior considering anticipated climate scenarios. Projections for future precipitation were obtained from the CNRM-CM6-1 Global Climate Model (GCM), which is part of the Coupled Model Intercomparison Project Phase 6 (CMIP6), and subsequently downscaled through the Long Ashton Research Station Weather Generator (LARS-WG) according to two Shared Socioeconomic Pathways (SSPs): SSP2-4.5 and SSP5-8.5. The precipitation data, downscaled to the local scale, were integrated into the HEC-HMS model to forecast future river discharge and investigate possible changes in low-flow characteristics. The 7Q10 low-flow index, which is defined as the minimum average flow in a continuous seven-day period with a recurrence interval of ten years was used for estimating and comparing low-flow characteristics. The model parameters were calibrated and validated using historical data from 1997 to 2019. Three objective functions namely: Nash-Sutcliffe Efficiency (NSE), Mean Relative Absolute Error (MRAE), and Percent Error in Peak Flow (PEPF) were used for optimizing model parameters. Future precipitation was projected for short-term (2021-2040), medium-term (2041-2060), and long-term (2061-2080) durations. The projected precipitation data was subsequently input into the developed HEC-HMS model to obtain future streamflow projections for the specified periods. The results of the climate change scenario analysis showed that precipitation may vary due to climate change within the range of -16 % to -5 % for the 2021-2040 period, - 4 % to 1 % for the 2041-2060 period, and 1 % to 21 % for the 2061-2080 period. The results indicated a likely increase in low-flow values across both SSP scenarios. The flow-duration analysis showed that the Q90 flow, representing the flow level that exceeds 90% of the time, is expected to increase, reflecting an upward change in streamflow for low-flow conditions. These findings are important for water resource managers working in the area to plan for and adapt to the impacts of altered low-flow regimes that can impact water supply, agriculture, and overall ecosystem health. Further studies should consider incorporating the use of hydrological models coupled with diverse climate scenarios to better capture the uncertainties related to climate predictions and land-use changes. These would provide a better understanding of the impacts of climate change on river basin hydrology in dry regions like the Maduru Oya River Basin.
item: Conference-Abstract
Assessment of disaster resilience in hospitals: a case study based framework development for Sri Lankan context
(Department of Civil Engineering, University of Moratuwa, 2024) Marasinghe, MMGC; Damruwan, HGH; Siriwardana, CSA; Dhanapala, S; Wijesekara, N; Wedamulla, A; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Hospitals are essential infrastructures that must maintain continuous operation during and after disasters to ensure the safety of patients and staff while providing medical services, even under surge conditions. Given the critical nature of these facilities, assessing their disaster preparedness is of utmost importance. This study addresses the limitations of the World Health Organization's Hospital Safety Index (HSI) when applied to Sri Lankan hospitals, leading to the development of the Structural Safety of Hospitals Assessment for Sri Lanka (SSH-SL). The study presents a comprehensive framework for evaluating hospital safety, divided into three primary modules: structural safety (utilizing SSH-SL), functional safety, and emergency and disaster management. Enhancements were made to the latter two modules to better align with the specific needs of the Sri Lankan context. The framework introduces a set of equations to calculate the safety index for each module, which then assigns safety levels and provides recommendations for improvement. This framework was applied to assess 15 government hospitals, revealing significant concerns across all three modules, underscoring the need for targeted interventions to enhance hospital resilience in Sri Lanka. The results from the assessment indicate that the structural safety levels of the 15 hospitals are generally at or above average level, suggesting that these facilities can operate during disaster conditions, though steps must be taken to ensure safety of both patients and staff. In terms of functional aspects, the majority of hospitals demonstrated a safety level of average or above, with two hospitals exhibiting below-average safety levels. Regarding Emergency and Disaster Management, 11 out of the 15 hospitals displayed high safety levels, whereas two hospitals had low safety levels. Immediate actions are necessary for hospitals with below-average safety levels, with a focus on implementing both short-term and long-term remedies. Additionally, limitations of the framework were identified during the hospital assessment process. The architectural safety submodule, under functional safety, was recognized as a critical submodule requiring modifications. Several assessment criteria specific to the Sri Lankan context were identified and subsequently incorporated into the existing submodule. Following these adjustments, a Delphi Study was conducted on the enhanced submodule, utilizing a panel of experts to gauge their consensus. Based on the survey results from the Delphi Study, weights were assigned to each assessment criterion within the submodule, leading to the derivation of a comprehensive safety score for the architectural safety of hospital buildings.
item: Conference-Abstract
Behaviour of rock socketed pile groups
(Department of Civil Engineering, University of Moratuwa, 2024) Gunasekara, HWP; De Silva, LIN; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Rock socketed pile groups are extensively employed in the construction industry due to their effectiveness in maximizing space utilization while supporting substantial structural loads, thereby enabling efficient vertical construction. This technique is particularly relevant in Sri Lanka, where bedrock is frequently encountered at shallow depths. However, despite the widespread use of rock socketed pile groups, the accurate determination of their bearing capacity remains insufficiently explored in existing literature. The conventional method, which involves simply aggregating the bearing capacities of individual piles, often lacks precision and necessitates further investigation. This study seeks to characterize the behaviour of rock socketed pile groups by estimating their bearing capacity, taking into account key parameters of pile groups such as pile spacing, socket length, and bedrock properties, as well as evaluating the overall efficiency of these pile groups. This study aims to achieve objectives through a thorough three-dimensional finite element (FE) analysis. This analysis involves developing a detailed model to assess the impact of key parameters of the pile group on both the bearing capacity and efficiency. This study seeks to confirm the accuracy and relevance of the finite element analysis results by cross-referencing them with experimental data from local sources. The study employs instrumental pile load test (IPT) data from a 1200 mm diameter, 10 m long test pile, implemented in the Port Access Elevated Highway project in Sri Lanka, to validate the FE model. The initial elastic modulus achieved 67% accuracy, which improved to 70% when doubled, and reached a peak of 75% with a tripled elastic modulus. Following model validation, a comprehensive FE analysis was conducted, adjusting bedrock properties and pile group parameters such as spacing and socket length to assess bearing capacity and group efficiency. The study focused on 2x2 pile groups, each with a 1200 mm diameter, assessing group efficiency by comparing individual pile performance to behaviour of the entire group. Increasing the spacing between piles does not affect the settlement for pile groups embedded in very strong bedrock. Similarly, extending the socket length for pile groups in very strong bedrock also does not alter settlement. In such cases, group efficiency remains constant regardless of changes in pile spacing or socket length, and the efficiency typically exceeds 1. In contrast, for pile groups installed in weak bedrock, increasing the spacing between piles leads to greater settlement, while extending the socket length results in reduced settlement. For these weaker bedrock conditions, group efficiency improves with increased socket length but declines with greater pile spacing. Despite these variations, group efficiency remains below unity for weak bedrock, though it approaches unity as socket length increases. The study shows that current practice method is effective for pile groups in strong bedrock but less reliable in weak bedrock. It emphasizes the need to account for group parameters and bedrock conditions when selecting rock socketed pile groups for effective structural load support.
item: Conference-Abstract
Cellular pile raft foundations for lightweight multi-storey buildings
(Department of Civil Engineering, University of Moratuwa, 2024) Sandamal, NGTM; Jayasinghe, MTR; De Silva, LIN; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
The global demand for housing and urban land scarcity has driven the need for multistorey buildings. The substructure design plays a crucial role in ensuring the stability of these structures, as traditional foundation methods, like piled or piled raft foundations, are essential for distributing the substantial loads. However, the high costs associated with these systems have prompted the e ploration of alternative foundation designs This study’s approach seeks to optimize foundation construction by reducing costs without compromising structural integrity, making it a viable solution for sustainable urban development. This study investigates the feasibility of employing a raft foundation, particularly a weight-compensated cellular raft design for multistorey buildings exceeding 10 floors which typically require costly pile foundations. Unlike traditional piles, Backhoe loaders are proposed for constructing piles filled with Aggregate Base Course (ABC) with cement and inserting reinforced columns for anchoring the cellular raft. The strategy involves settling the building slightly to mobilize the soil capacity, particularly for sandy clay soil conditions. Furthermore, the study explores the potential of lightweight superstructures to significantly reduce construction costs by optimizing structural weight and eliminating the need for pile foundations. Specifically, it explores the utilization of Expanded Polystyrene (EPS) based lightweight panels and precast prestressed concrete beam systems with precast prestressed concrete slabs. Investigating a 10-story reinforced concrete moment resisting frame (MRF) supported by a cellular piled raft foundation, the research employs a direct approach considering soil-structure (SSI) interaction effects. Through construction stage analysis using finite element software (Midas GEN, Midas GTS NX), the study determines optimal gap sizes for the cellular raft and assesses the maximum number of storeys feasible without pile foundations. Overall, this study suggests that on sandy clay soil, constructing taller buildings with a maximum of 14 floors, in addition to the cellular basement, is feasible using lightweight superstructures in conjunction with cellular rafts. Moreover, the research recommends increasing pile spacing beyond the current 5m x 5m grid configuration to fully mobilize soil capacity. Future studies should also investigate the effectiveness of these foundation systems across various soil types, including silty clay, loamy soil, and sandy loam, to further validate the design's applicability in different geological conditions.
item: Conference-Abstract
Construction quality framework for school buildings in Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2024) Thoradeniya, BRWMD; Jayasinghe, C; Ariyaratne, IE; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
The built environment of schools plays a crucial role in shaping the educational experience, yet Sri Lanka has faced ongoing concerns regarding the quality of school construction, despite significant government investment in education. To address this issue, a comprehensive study was conducted with the primary objective of developing a construction quality framework specifically tailored for school buildings in Sri Lanka. This framework aimed to establish clear standards and guidelines for the design, construction, and maintenance of school buildings, ensuring that they meet the necessary safety, functionality, and sustainability criteria. An extensive literature review was undertaken to systematically break down the processes involved in school building construction and to conduct background research on contemporary quality standards. The breakdown included the following key phases: project initialization, design and construction, operations and maintenance, and rectification and building condition. Data collection was carried out through multiple methods, including case study reports from the National Building Research Organization (NBRO), which covered 58 buildings across 22 schools. Surveys of school stakeholders and expert interviews were also conducted. The NBRO reports included visual observations and both destructive and non-destructive testing techniques. The survey aimed to assess the efficiency of operations and maintenance processes, while expert interviews provided insights into the procurement procedures of school buildings. The collected data were analysed using statistical methods to categorize and prioritize the defects identified in the construction process. This analytical approach facilitated the identification of the most common and critical defects, along with their correlation to the overall condition of the buildings. The defects were categorized based on their location and severity, offering a clear understanding of recurring issues in school construction. The analysis revealed significant issues in design, construction, and maintenance practices, with gaps in maintenance protocols and challenges such as financial constraints and bureaucratic delays. The importance of addressing these defects proactively, particularly in critical structural elements such as slabs, columns, and beams, was emphasized to ensure the durability and safety of school buildings. The proposed framework was validated through its application to a school building construction project in the Northwestern Province, which encompassed two phases—one completed and the other ongoing. This validation demonstrated the framework's effectiveness in improving construction quality and addressing prevalent issues. The outcomes of this methodological approach provided valuable insights into the construction quality of school buildings in Sri Lanka. By identifying and prioritizing defects throughout the entire construction process, the study established a basis for minimizing or eliminating these issues in future construction projects. The insights gained from this research contribute to the formulation of targeted construction guidelines for school buildings in Sri Lanka, aligning with the evolving needs of the Sri Lankan education system.
item: Conference-Abstract
Design guidelines for lateral clearance at horizontal curves in expressways
(Department of Civil Engineering, University of Moratuwa, 2024) Harshana, AWAKD; Mampearachchi, WK; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Design guidelines for lateral clearance re uire designing e pressways by confirming drivers’ line of sight is not obstructed by the objects at the horizontal curves. It gives sufficient sight distance to drivers ensuring safety of drivers and passengers. There are guidelines for lateral clearance design such as AASHTO Green Book. In the expressway, lateral clearance is measured from the centreline of the inner lane to the guard rail. Lateral clearance distance is varied with the radius of the curve and speed of the vehicle. Sometimes widening should be done to reach the re uired lateral clearance If the driver’s line of sight isn’t obstructed by guard rail, there is no requirement to go for road widening with additional cost. This study was done to evaluate whether the existing lateral clearance is enough to fulfil the lateral clearance guidelines for various radii of curves and speeds. Subsequently, if the existing clearance is not enough, the line of sight is obstructed by the guard rail is checked, by using road geometry, height of guard rail and design speed. If the available lateral clearance is not enough at the centreline of the road, widening must be done because, even the line of sight is not obstructed by the guard rail, line of sight can be obstructed from vehicles that are going in the other direction. But at the outer shoulder sometimes even the available lateral clearance is not enough, widening is not necessary because the line of sight is not obstructed by guard rail. Therefore, drivers can see sufficient stopping sight distance. This research underscores the critical importance of lateral clearance in ensuring the safety of expressways, particularly at horizontal curves. By verifying the effectiveness of design guidelines, such as those outlined in the AASHTO Green Book, the study highlights the necessity of maintaining adequate lateral clearance to preserve drivers' line of sight and prevent potential accidents. The findings reveal that while widening roadways may be necessary in cases of insufficient lateral clearance, careful consideration of factors such as curve radius, design speed, and superelevation is essential. Moreover, the study emphasizes the paramount importance of prioritizing safety in roadway design, underscoring the need to implement measures that guarantee an unobstructed line of sight for drivers. According to the results, at inner shoulder, if sufficient lateral clearance is not provided, even driver’s line of sight doesn’t cross the guard rail, road widening is necessary Because in such situations, the driver’s line of sight crosses by the vehicles coming from opposite direction. At the outer shoulder, for the 120 kmph design speed, if the radius is less than 1650 m, the initial and final 250 m of the curve should be widened. Also, for the design speed of 110 kmph, if the radius is less than 1300 m, the initial and final 220 m distance of the curve should be widened. The initial and final 185 m distance of the curve should be widened for a design speed of 100 kmph if the radius is less than 900 m. If the radius is less than 695 m for a design speed of 90 kmph, the initial and final 160 m of the curve should be widened. So, at least 33% of road widening costs can be saved from the recommended suggestions, without affecting the safety of drivers and passengers.
item: Conference-Abstract
Design-informed optimization of 2D skeletal structures using convolutional neural networks
(Department of Civil Engineering, University of Moratuwa, 2024) Jayaweera, JANN; Herath, HMST; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Structural optimization aims to find the most efficient material distribution within a design domain by minimizing material usage, self-weight, and strain energy, while maximizing strength. Optimization approaches often use compliance as the objective function and volume as a constraint, which can result in designs that may not fully meet the practical requirements of civil and structural engineering due to potential inadequacies in structural integrity. To address this issue, design-informed optimization integrates structural optimization with design codes such as EN 1993-1-1, ensuring that optimized designs comply with structural integrity requirements and real-world applicability. Existing design-informed optimization algorithms typically rely on iterative schemes, which are computationally intensive and require specialized expertise. To overcome these challenges, this study introduces a novel computer vision-based framework that predicts design-informed optimized frames and accurately identifies member sizes using image processing techniques coupled with probabilistic section classifiers. This framework utilizes input parameters such as span, height, and load to predict the topology, size, and layout of optimized frames that satisfy structural adequacy criteria. It is particularly beneficial for assembly-based manufacturing, where precise member section prediction is crucial for construction efficiency and material optimization. The framework consists of three stages. In Stage 1, the CNN64 model generates a low-resolution layout of the optimized frame using input parameters such as span, height of the design domain, and load. In Stage 2, the CNN512 model refines this layout to produce a high-resolution image of the optimized frame, where section sizes are assigned. These models are trained on varying parameters including fixity, design domain, and load conditions. Stage 3 involves a member section identification algorithm that classifies the optimal structural section sizes through image processing techniques. The efficacy of the framework was validated using simply supported and cantilever beam datasets, achieving pixel accuracies of 94.6% and 91.8%, respectively. Post-calibration, the section identification algorithm, which accounts for unavoidable errors such as generator residuals and section identification errors, achieved near 100% accuracy, demonstrating the robustness of the probabilistic section classifier. Compared to alternative architectures, the CNN64+CNN512 framework consistently outperformed others in metrics such as pixel accuracy, true positive rate, and binary cross-entropy in both datasets. It also demonstrated a significant reduction in computational loss, further confirming its computational efficiency. Overall, the analysis reveals that the CNN64+CNN512 model not only provides superior performance in prediction accuracy but also strikes an effective balance between computational efficiency and model complexity.
item: Conference-Abstract
Development of a damage assessment matrix for load-bearing masonry houses
(Department of Civil Engineering, University of Moratuwa, 2024) Thalpage, SL; Jayasinghe, C; Ariyaratne, IE; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Masonry houses are common types of buildings constructed using materials like bricks, stones, or concrete blocks. They are popular due to their durability and aesthetic appeal. However, as masonry structures age, they become vulnerable to various forms of crack damage that can potentially compromise their structural integrity and the safety and comfort of their occupants. While numerous studies have examined the condition assessment of buildings, they primarily rely on visual inspection conducted by inspectors who often base their evaluations on personal experience, biases, and risk attitudes. Recognizing the absence of a standardized method for assessing wall crack damages, this research study was aimed at developing a crack damage assessment matrix specifically focusing on single-story, load-bearing masonry houses. A database surrounding over 270 instances of cracks in approximately 60 houses from the Higurankgoda area in Sri Lanka, is considered to determine the key factors influencing the damage severity and safety of the house. Severity considerations include crack length, width, and number of cracks in the wall, while safety factors encompass crack severity level, separation level of the crack, surface condition of the cracked wall, crack location, crack direction, and structural degradations. To construct a data-driven prioritization matrix, the study employs the Analytical Hierarchy Process (AHP) and a probability-based approach, utilizing real-world data to assign reliable weightage to each parameter. This research determines the influence weightage of each parameter on overall safety and stability. The calculated weightage results indicate that the parameter with the highest impact is from the structural degradations, while the parameter with the lowest impact is from the crack direction. This matrix facilitates a Risk Level Index (RLI) to assess the overall impact of individual cracks and a systematic approach is proposed to determine the overall risk level of the house. The systematic approach illustrates the risk level for the house when it has varying numbers of wall cracks based on the generated RLI value and the number of cracks in each influence category. Fifteen single-story load-bearing masonry houses were selected for the testing and verification of the developed matrix, and the outcomes of the matrix were compared with the already assigned risk levels by experts for each house. The proposed matrix was tested and validated with more than 80% accuracy level. This prioritization matrix will empower engineers, and homeowners to efficiently prioritize repair efforts and allocate resources based on potential risk. The proposed approach integrates advanced analytical techniques with practical insights to enhance decision-making in addressing wall crack damages in masonry houses.
item: Conference-Abstract
Development of an optimum mix for paving blocks using waste steel slag and crushed tile waste as part replacement of aggregates
(Department of Civil Engineering, University of Moratuwa, 2024) Nirainenchan, J; Gamage, JCPH; Chandrathilaka, ERK; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
In contemporary construction practices, paving blocks are essential for creating durable and aesthetically pleasing surfaces in urban and suburban areas, such as pedestrian walkways, driveways, and plazas. However, traditional paving blocks are often associated with considerable weight and high production costs, which can limit their widespread use and contribute to environmental degradation due to the extensive use of natural aggregates. This research aims to address these challenges by developing a lightweight and cost-effective mix design for eco-friendly paving blocks. The proposed design incorporates waste materials from the steel industry, specifically steel slag, as well as crushed tile waste from construction industry, both of which are typically discarded as industrial and construction waste. By repurposing these materials, the study seeks to minimize the environmental impact of paving block production while providing a sustainable and economical alternative to conventional paving blocks. The experimental program involved replacing traditional fine aggregates in the paving block mix with steel slag at varying proportions of 10%, 20%, and 30% by volume. Additionally, coarse aggregates were partially substituted with 25% crushed tile waste. The mechanical performance of the various paving block mixes was thoroughly assessed through a series of standardized tests, including density, compressive strength, split tensile strength, and flexural strength. These tests were conducted to determine the structural integrity and suitability of the eco-friendly paving blocks for practical applications. The results of the study revealed that the paving block mix containing 30% steel slag and 25% crushed tile waste achieved an optimal balance between weight reduction, cost efficiency, and mechanical performance. This mix exhibited a compressive strength of 16.6 MPa after 28 days, making it suitable for non-traffic areas such as walkways, garden paths, and recreational spaces. Although this strength is marginally lower than the compressive strength of 17.5 MPa observed in conventional paving blocks, the eco-friendly mix offers several advantages, including a significant reduction in weight and production costs. Furthermore, a detailed cost analysis was performed to compare the economic feasibility of the eco-friendly paving block mix with that of traditional paving blocks. The analysis indicated that the use of waste materials such as steel slag and crushed tile waste not only reduces the consumption of natural resources but also results in considerable cost savings. The cost of paving blocks decreases with the substitution, showing a reduction rate of approximately 4.6% from Mix 01 to Mix 02, and continuing consistently up to Mix 05, making it economically feasible. In conclusion, this study contributes to the ongoing efforts to develop sustainable construction materials by demonstrating the viability of using industrial and construction waste in paving block production.
item: Conference-Abstract
Development of bond stress-slip models for CFRP / concrete bond exposed to mild acidic exposure
(Department of Civil Engineering, University of Moratuwa, 2024) Ravidu, AKS; Chandrathilaka, ERK; Gamage, JCPH; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Carbon Fiber Reinforced Polymer (CFRP) is widely used in various industries due to its excellent mechanical properties, including a high tensile strength-to-weight ratio and resistance to corrosion. However, the bond performance of CFRP with concrete can be adversely affected by exposure to mild acidic environments, which can originate from sources such as acidic rains, soil, sewage, and industrial activities. This study focuses on developing an understanding of the bond stress-slip behaviour of CFRP/concrete joints exposed to acidic conditions, specifically examining the impact of different bond curing temperatures and exposure periods in a mildly acidic environment. The experimental results, obtained from a previous study, involved CFRP/concrete single-lap shear specimens exposed to a sulphuric acid solution with a pH value of 2 for 15, 30, and 90 days. Those specimens were cured at ambient temperature (28 °C), 65 °C, and 75 °C to investigate the effects of curing conditions on bond performance. The experimental results from that study provided data on load-displacement behaviour and failure modes under those varying conditions. Complementing the experimental work, a finite element model (FEM) was developed using a commercially available finite element software to simulate the bond behaviour of CFRP/concrete joints. A modified version of Simplified concrete damage plasticity model was used as the material model for concrete, while a linear elastic model was employed for the CFRP, and the adhesive was modelled using a damage evolution model to account for potential degradation. The numerical model was validated against the experimental data, showing a strong correlation in predicting the load-displacement behaviour of the joints under different curing and exposure conditions. The results of the study indicated that curing temperature significantly influenced the bond strength of CFRP/concrete joints. Specimens cured at 65 °C exhibited the highest failure loads, suggesting that elevated temperature curing enhanced the bonding mechanism. However, curing at temperatures beyond the glass transition temperature (Tg) of the epoxy resin resulted in a reduction of bond strength. Furthermore, prolonged exposure to acidic environments degraded the bond strength, with noticeable reductions observed after 90 days of exposure. This degradation is due to chemical reactions with the acid that weaken the bond interface. Parametric studies were also conducted to assess the effects of adhesive layer thickness and different types of CFRP on bond performance. An adhesive thickness of approximately 1 mm was found to be optimal for maximising bond strength. Additionally, the use of CFRP with a higher modulus showed marginal improvements in joint strength but did not significantly alter the overall failure behaviour when exposed to a mildly acid environment
item: Conference-Abstract
Effect of crease curvature on bending stiffness in curved crease origami
(Department of Civil Engineering, University of Moratuwa, 2024) Weerasekara, WMHGLCB; Mallikarachchi, HMYC; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Deployable systems play a vital role in design optimisation of spacecrafts. Limited payload capacity in launch vehicles often conflicts with the demand for large-area systems required for better performance in the operational phase. The art of origami enables the storage of a large surface structure in a compact volume by utilising plastically deformed fold lines known as creases. Origami can be categorised into two types as straight crease origami and curved crease origami based on the geometry of the crease. Straight crease origami demonstrates rigid foldability while curved crease origami facilitates smooth and efficient folding by incorporating panel bending. The use of curved creases in deployable membranes reduces the required number of creases compared to straight creases ultimately leading to less production time and better quality deployed surface. The bending stiffness of the crease and the external force required to fold the membrane are key aspects that influence the packaging efficiency. The main objective of this research is to assess the effect of crease curvature on the bending stiffness of curved creases. The study encompassed quasi-static folding and unfolding experiments of curved-crease specimens with different crease radii made of 80 gsm printer paper to understand crease behaviour. Furthermore, numerical models were developed to simulate the crease behaviour of curved creases and validated against experiments in order to develop prediction tools for future designs. The resistive force resulting in bending a curved crease specimen was measured experimentally for rectangular specimens with overall dimensions of 60 mm × 100 mm while varying crease radii from 35 mm to 75 mm. Additionally, the force-displacement response was recorded for flat sheets with dimensions of 50 mm × 60 mm and 100 mm × 60 mm to compare the bending stiffness of curved creases to that of a flat sheet having similar overall dimensions. The results demonstrate that the initial bending stiffness of curved-crease specimens with a low crease radius is lower but becomes higher at the maximum folded state compared to specimens with a high crease radius. Additionally, it was observed that the contribution of the unrestrained half of the specimen significantly increases the bending stiffness of a curved crease specimen during the folding motion for lower crease radius, whereas the contribution remains almost constant for higher crease radius. Numerical models of curved creases, developed in the commercial software Abaqus using a segmented curved-crease modelling approach incorporating straight crease characteristics, accurately estimate experimental reaction forces, indicating that the characteristics of straight creases can be used in modelling curved creases.
item: Conference-Abstract
Effect of locally manufactured graphene oxide on concrete strength
(Department of Civil Engineering, University of Moratuwa, 2024) Elapatha, EGV; Halwatura, RU; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
The research investigates the impact of locally manufactured Graphene Oxide (GO) from Ceylon Graphene Technologies on the properties of concrete, focusing on compressive strength, sorptivity, early heat of hydration, and SEM analysis, to determine if GO can be a cost-effective method for concrete construction. Three concrete grades were tested with varying GO concentrations (0.02%, 0.04%, 0.06%) and compared to control samples at 7- and 28-day curing periods. For grade 25 concrete, the compressive strength increased by 24.84% to 52.58% at 7 days and 13.82% to 46.74% at 28 days for GO concentrations of 0.02% to 0.06%, respectively. Grade 30 concrete exhibited even more substantial improvements, with compressive strength increases of 44.1% to 68.34% at 7 days and 11.9% to 27.45% at 28 days for the same GO concentrations. Grade 35 concrete showed modest gains, with 7-day increases of 10.5% to 10.534% and 28-day increases of 2.98% to 16.59%. These results demonstrate that higher GO concentrations lead to more significant enhancements in compressive strength, underscoring GO's potential to improve concrete strength and durability cost-effectively. In addition to compressive strength, sorptivity tests on grade 30 concrete samples revealed that higher GO content results in lower water absorption rates. This reduction in sorptivity indicates enhanced durability and resistance to water ingress, crucial for the longevity of concrete structures. The early heat of hydration tests on grade 30 concrete indicated that GO increases heat production during the hydration process, with temperatures rising as GO percentages increased. This dose-dependent impact suggests that GO accelerates the hydration process, contributing to quicker strength gain. SEM analysis provided further insights into the microstructural changes induced by GO. The SEM images of GO-mixed concrete showcased a significant increase in hydrated products compared to conventional concrete. These findings highlight the ability of GO to improve infrastructure durability by reducing sorptivity and enhancing structural resilience. The integration of GO into concrete formulations can lead to more durable and resilient structures, offering substantial benefits for the construction industry. GO's ability to enhance concrete properties suggests it could be a cost- effective, transformative material for future infrastructure projects. The study concludes that incorporating GO into concrete not only boosts its compressive strength but also reduces water absorption and accelerates the hydration process. These improvements, evident across different concrete grades and GO concentrations, indicate that GO is a promising additive for developing stronger, more durable concrete in a cost-effective manner. The research provides valuable insights for future studies and practical applications, suggesting that GO can significantly contribute to the advancement of construction materials and methods, ultimately leading to more robust and enduring infrastructure.
item: Conference-Abstract
Effect of preloading and endplate imperfections in bolted connections: Moment-rotation characteristics through explainable artificial intelligence
(Department of Civil Engineering, University of Moratuwa, 2024) Dharmawansha, DAST; Herath, HMST; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Stainless-steel is a popular engineering material due to its durability, high resistance to corrosion, aesthetic appeal, ease of construction and maintenance, recyclability, and ductility. It is often used in a wide range of structural engineering applications such as frames, buildings and bridges. Across these diverse applications, steel connections are a crucial component as they ensure the unified performance of the structure. This study investigated the effect of bolt preloading, endplate imperfections, and geometric parameters on the connection moment rotation response of extended endplate bolted connections. This study employed a validated numerical model against experimental results from the structural testing laboratory of the University of Moratuwa, further validated against experimental results available in the literature. The validated numerical model was then used to investigate the impact of varying levels of bolt preloading and imperfections on rotational stiffness. The results showed that rotational stiffness increases by 134% with ultimate preloading. Residual deformation from welding causes initial imperfections in bolted endplate connections, with V-shape, C-shape, and W-shape imperfections identified in the literature. This study examines the impact of C-shape and V-shape imperfections on rotational stiffness. The results indicate that V-shape imperfections have minimal influence if the level of imperfection is limited to the criterion of (endplate depth)/300, while C-shape imperfections significantly affect rotational stiffness, even within acceptable limits. A novel explainable machine learning approach was utilized to investigate the influence of geometric parameters on the moment-rotation response of connections. A comprehensive numerical modelling approach (validated using related work) was used to generate data for various input features, such as endplate thickness, bolt diameter, overall section width, overall depth, web thickness, flange thickness, vertical bolt spacing, and horizontal bolt spacing. An artificial neural network (ANN), extreme gradient boosting (XGB), random forest (RF), and k-nearest neighbours (KNN) were employed alongside Shapley additive explanations (SHAP) to interpret the trained models. Analysis shows that endplate thickness strongly governs the moment-rotation behaviour of the bolted endplate connections. Moreover, SHAP explanations align with the generally accepted behaviour of steel extended endplate bolted connections according to EN 1993-1-8.
item: Conference-Abstract
Effect of tie beams on the behavior of isolated foundation systems
(Department of Civil Engineering, University of Moratuwa, 2024) Gunathilaka, LTD; De Silva, LIN; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
The stability of isolated foundation systems is crucial to the structural integrity and safety of buildings, especially in regions with varying load conditions. Tie beams, widely used to connect isolated footings, play an integral role in this process. However, their impact on bearing capacity and settlement characteristics is often overlooked in standard analyses. This research primarily aimed to explore the influence of tie beams on the settlement characteristics and overall performance of isolated foundation systems. A comprehensive methodology combining both model experiments and finite element analysis (FEA) was employed to achieve these objectives. Initially, two model experiments were conducted using small-scale prototype structures: one with a single isolated footing and another with two footings connected by a tie beam. These experiments aimed to validate the FEA results by comparing the experimental settlement data with the simulated outcomes. Two distinct models of the foundation system were developed, each based on a typical three-story building with 16 isolated footings. This setup was designed to simulate a realistic structural scenario and evaluate the impact of tie beams under varying loading conditions. The footings were loaded with varied loadings in the range of 350 kN to 1300 kN to simulate real-world scenarios. One model included tie beams connecting the footings, while the other omitted them, allowing for a comparative analysis of their effects on settlement and structural integrity. The findings reveal that incorporating tie beams significantly reduces the maximum individual settlement, with a decrease of up to 22 mm (43%). Furthermore, the inclusion of tie beams narrowed the variation in settlement across individual footings, resulting in a more uniform distribution of settlements. Differential settlements were notably reduced, with all values staying under 2 mm, reflecting a 92% reduction compared to the model without tie beams. In conclusion, the inclusion of tie beams significantly reduces both settlements and differential settlements, contributing to a more uniform distribution of loads across isolated foundation systems. While positioning tie beams at the footing level may further reduce settlements, it also increases the forces acting on the tie beams, necessitating higher reinforcement and potentially leading to increased construction costs. The research recommends maintaining tie beams at ground level in general construction practices, except in scenarios where minimizing settlements is critically important. This study underscores the significance of tie beams in enhancing the performance and stability of isolated foundation systems, highlighting their essential role in mitigating settlement-related issues.
item: Conference-Abstract
Effect of urban vegetation cover on CO2 reduction in the city
(Department of Civil Engineering, University of Moratuwa, 2024) Chanika, HKP; Weerasinghe, N; Halwatura, RU; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Rising urban carbon dioxide levels have emerged as a critical issue due to their adverse effects on public health and the environment. Trees are a natural and sustainable solution to mitigate urban carbon dioxide (CO2) concentrations, as they absorb CO2 from the atmosphere through photosynthesis. However, the specific relationship between tree density and CO2 concentration within cities is unclear. The main objectives of this research are to determine the relationship between tree density and CO2 concentration reduction in cities and to identify the optimum tree density to reduce the CO2 level in the city to obtain the required CO2 level. For this study, data were collected in the densely urbanized city of Colombo and various urban areas within the Hambantota district. Tree densities and CO2 concentration reduction data were collected from 300 sample plots, each with a fixed size of 50m x 50m, near roads in selected urban areas. When calculating tree density, it is important to calculate canopy volumes of trees. It depends on canopy height, crown diameter and canopy shape. The tree density of the sample plot was calculated by dividing the total canopy volume by the area of the sample plot. A digital portable CO2 meter was used to measure the CO2 level. First the CO2 concentration was measured at the centre of the road and then the CO2 concentration was measured at the centre of the sample plot. The reduction in CO2 level was calculated by the difference between these two readings. By analysing tree densities and CO2 concentration data collected through field data studies, a linear relationship was obtained between tree density and CO2 concentration reduction in urban areas. The plotted line got a R2 value of 0.8806 indicating a well-fitting model. Therefore, this linear plotted line can be described as a reasonable fitted line representing all collected data. Also, the data was classified based on the CO2 concentration in the centre of the road and the behaviour of the CO2 concentration reduction Vs tree density relationship was studied in each range. A linear relationship was obtained in each of those ranges. When all the collected data were classified as residential and non-residential based on the usage of the sample plots, the R2 values obtained from those graphs were higher than the R2 value of the graph drawn without classification. The R2 value of the graph for non-residential areas has increased relative to the value of the graph for residential areas. Accordingly, classifying in this manner led to an increase in the accuracy of the relationship. Using these relationships, the optimum tree density required to obtain the required CO2 reduction in urban areas can be identified. The results of this study will be valuable for policymakers and urban planners looking for ways to improve air quality and create more sustainable urban environments.
item: Conference-Abstract
Enhancing streamflow prediction in Sri Lankan River Basins using AI models: A comparative study of wet and dry zones
(Department of Civil Engineering, University of Moratuwa, 2024) Karunarathna, SMSD; Rajapakse, RLHL; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Artificial Intelligence (AI) techniques have gained significant attention in recent years for their application in various engineering domains, including hydrology. Groundwater modelling, streamflow prediction, precipitation forecasting, temperature forecasting, and time series generation for rainfall are some of the hydrological applications that have benefited from AI techniques. In Sri Lanka, water resource management is challenging due to the country's geographical characteristics, seasonal rainfall patterns, and growing water demands. Traditional methods used in water resource management have limitations and rely on complex parameters, which often result in less accurate predictions of rainfall-runoff, flood events, and drought conditions, impeding effective water resource management. To enhance water resource management practices in Sri Lankan River basins, AI methodologies were integrated into hydrological modelling. Two river basins were chosen as representatives of the wet and dry zones in Sri Lanka: the Ellagawa sub-basin from the Kalu River basin for the wet zone, and the Thanamalwila sub-basin from Kirindi Oya basin for the dry zone, covering the period from October 1, 2000, to September 30, 2011. The pivotal recurrent neural network (RNN) architectures such as Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU) are highly effective for modelling time series data, especially when it comes to streamflow prediction. These models are excellent at capturing temporal dependencies, which is significant for streamflow as it depends on previous data and weather. In this study, both the physically-based semi-distributed HEC-HMS hydrological model and AI models such as RNN-LSTM and RNN-GRU were applied to evaluate their predictive capabilities in streamflow forecasting. The performance of these models was assessed using objective criteria including Nash-Sutcliffe Efficiency (NSE), Mean Ratio of Absolute Error (MRAE), and the coefficient of determination (R²). The observed and predicted streamflow hydrographs and flow duration curves (FDC) were generated to evaluate model goodness of fit and time series graphical comparability. The study findings indicate that the LSTM model is superior to both the GRU and HEC-HMS models in predicting streamflow, with an MRAE of 0.42 and NASH of 0.82 for the LSTM model in wet zone river basins. The LSTM algorithm used the best values of R2, which were 0.88 and 0.87 for the testing and training phases, respectively. The proposed model may be used to develop other basins in the wet zone. However, for the Thanamalwila sub-basin, the results of both AI and physical-based models were poor, likely due to inaccurate input features and inherent mismatches between rainfall and streamflow. Better input features are essentially required to improve the model training and simulation process. Therefore, the integration of AI techniques presents an opportunity for Sri Lanka to overcome existing limitations in hydrological modelling and enhance its resilience to water-related challenges. By embracing innovative approaches and leveraging available data, Sri Lanka can strengthen its capacity for water resource management and adaptation to climate change impacts, ultimately fostering sustainable development and resilience in the face of evolving environmental conditions.
item: Conference-Abstract
Evaluating the effectiveness of treatment solutions on blue stain fungi growth in pine wood plantations in Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2024) Rathuge, LR; Hewage, IS; Mendis, MS; Halwatura, RU; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
The presence of blue stain fungi in pine wood plantations causes a significant challenge to the pine wood industry. Because of the visible discoloration due to the presence of fungi, it significantly reduces the market value of the wood. This study was conducted to explore the occurrence of blue stain fungi growth in pine wood plantations in Sri Lanka, with a focus on assessing the effectiveness of various wood treatment solutions. The research was conducted over six months, at a pinewood plantation in Bandarawela. The primary objective was to compare the effectiveness of different treatment solutions on the occurrence of blue stain fungi in treated versus non-treated wood samples. 27 wood samples prepared from freshly cut pine trees were used in this study. The samples were treated using four different solutions: two inorganic preservatives, Anti-blue and Anti-boron which are widely available in the market, and two innovative organic preservatives developed in Sri Lanka: Final Solution Without Mud (FSWOM) and Final Solution With Mud (FSWM). Samples were immersed in the solutions for 48 hours for the treatment, using the dipping method. To assess the impact of treatment timing, two sets of samples were prepared: one set was treated within 7 days of cutting, and another set within 7 to 14 days. To provide a baseline for comparison, a control set of non-treated samples was maintained. The results demonstrated that all treated samples showed significantly reduced blue stain fungi growth compared to the non-treated samples. Both inorganic preservatives, Anti-blue and Anti-boron, were highly effective in mitigating the blue stain fungi growth. Remarkably, the organic preservatives were also successful. FSWM was the most effective organic solution matching the performance of the commercially available inorganic preservatives. FSWOM, while slightly less effective than FSWM, still provided good protection against blue stain fungi, indicating the potential of organic solutions in wood preservation. It revealed that adding paddy field mud significantly enhanced the antifungal properties of these organic preservatives, approaching the level of effectiveness of the inorganic preservatives. Additionally, the study found that the timing of the treatment whether applied within 7 days or 7 to 14 days after cutting did not significantly affect the effectiveness of the treatment solutions. This implies that there is flexibility in the timing of treatment without compromising its effectiveness. The study concludes that both organic and inorganic preservatives are effective in mitigating blue stain fungi growth in pine wood. More specifically, the organic preservative FSWM provides an effective and environmentally friendly alternative to inorganic preservatives, thereby enhancing wood preservation techniques.
item: Conference-Abstract
Evaluating the impact of drought spatial distribution on river flow dynamics using remote sensing data
(2024) Madhumal, PVRP; Gunawardhana, HGLN; Pasindu, HR; Damruwan, H; Weerasinghe, P; Fernando, L; Rajapakse, C
Drought is a complex and challenging weather-related disaster with significant economic, social, and environmental impacts. Traditional drought monitoring, which primarily relies on ground observations, often falls short due to limited spatial coverage and data scarcity. Most existing drought indices focus on a single variable, which may not adequately capture the full scope of drought conditions. To address this, integrating multiple parameters from remote sensing data presents a promising approach, providing spatially distributed and real-time information for a more accurate and comprehensive drought analysis. This study aims to utilize multiple remote sensing parameters to provide a comprehensive analysis of droughts in the Padiyathalawa catchment area, a dry zone river basin in Sri Lanka covering 171 km². Three satellite-derived indices, namely the Vegetation Condition Index (VCI) and Temperature Condition Index (TCI), derived from Moderate Resolution Imaging Spectroradiometer (MODIS) data, and Standardized Precipitation (SP) from Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), were integrated using Principal Component Analysis (PCA) to derive a Combined Drought Index (CDI). In this analysis, Principal Component (PC) one, capturing 58% of the total variance, was used to develop the CDI. Validation showed a strong visual correlation between the normalized CDI and river flow over time. However, the Kolmogorov-Smirnov (KS) test revealed that the CDI needs improvement, as it does not fully capture streamflow dynamics during significant rainfall events. Despite this, the CDI effectively reflected seasonal variations, indicating dry conditions from June to August and wetter periods influenced by the northeast monsoon. Using the Hydrologic Engineering Center - Hydrologic Modeling System (HEC-HMS), the area was modelled as a semi-distributed system with five sub-catchments, based on the spatial variation of drought in developed 1 km resolution CDI maps. Model calibration was conducted for the period 1999-2005, followed by validation from 2005-2010, employing the Nash–Sutcliffe model efficiency coefficient (NSE) and mean relative absolute error (MRAE). The results indicated that the HEC-HMS model effectively simulated streamflow, with NSE values of 0.78 and 0.92, and MRAE values of 0.86 and 2.44. However, the model exhibited limitations in simulating low-flow conditions, failing to accurately represent discharges below 0.1 m³/sec. Further analysis of drought-prone areas identified by the CDI was performed using the HEC-HMS, incorporating hypothetical drought scenarios. The study found that river flow decreases as drought severity intensifies, with the impact lessening in sub-catchments farther from the catchment outlet. It highlights the potential of integrating remote sensing data, PCA, and hydrological modelling for effective drought assessment, benefiting farming communities and decision-makers in understanding drought severity on river flow and taking necessary action.

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