Institutional-Repository, University of Moratuwa

Welcome to the University of Moratuwa Digital Repository, which houses postgraduate theses and dissertations, research articles presented at conferences by faculties and departments, university-published journal articles and research publications authored by academic staff. This online repository stores, preserves and distributes the University's scholarly work. This service allows University members to share their research with a larger audience.



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Recent Submissions

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item: Thesis-Abstract
Manual method to find cable forces in extradosed bridges
(2025) Sampath, PPGRN; Baskaran, K
The first extradosed bridge was completed in 1994 and within the following three decades, this new bridge type has gained popularity due to its indistinguishable appearance to a cable stayed bridge. Balanced cantilever construction method was adopted in many of the extradosed bridges. Limited number of reference availability to study the extradosed bridges has limited the understanding of design concepts and practicing the designs among the engineers. Objective of this research is to develop a manual calculation method to determine the stay cable force for a prestressed concrete extradosed bridges constructed using balanced cantilever method. In addition, a detailed explanation about the design concepts, construction methods and comparison of extradosed bridge with other bridge types is also intended in this study. Determination of the stay cable force has been a challenging task for extradosed bridges due to its high statical indeterminacy. At present, modern bridge design software equipped with the required iteration functions are used mainly for this but no literature is available to manually approximate the stay cable force for an extradosed bridge constructed using balanced cantilever method. This research aims at bridging this gap and assisting the readers to understand all the basic concepts with regard to an extradosed bridge built using balanced cantilever method. Detailed literature review was conducted to understand the design concept and the initial sizing of the members. Based on the study, it was identified that the self-weight and the internal prestressing forces are the two main factors which affect the required final stay cable force. This was further verified using a computer analysis model developed using CSiBridge software. In developing a manual calculation method, it was assumed that the bridge behaves as a propped cantilever vertically supported at the stay cable anchorage locations. With the internal prestressing applied as a bending moment, self-weight applied as a uniformly distributed load (UDL) and the form traveller load applied as a point load at the cantilever end, stay cable force required was determined considering that the total displacement at cable anchorage location requires to be zero. Several assumptions were made in this simplified method and the stay cable force determined from the simplified method was found to be reasonably accurate compared with the actual force.
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Validity of AASHTO sight distances in geometric design of expressways in Sri Lanka
(2025) Perera, RAD; Mampearachchi, WK
Sight distance is a critical design parameter in the geometric design of highways, directly influencing their operational efficiency and safety, particularly under nighttime conditions. Stopping sight distance is a fundamental requirement for all types of highways, playing a key role in horizontal curves, crest vertical curves, and sag vertical curves, which are essential components of highway geometry. This research evaluates the validity of AASHTO sight distance criteria in the geometric design of expressways in Sri Lanka. The study involved analyzing accident data from the Southern Expressway to identify critical locations and reviewing their design compliance with AASHTO guidelines. Additionally, sight distance variations were compared with geometric design standards of other guidelines, such as Japan, Australia, Austria, Britain, United States, Canada, France, Germany, Greece, South Africa, Sweden, and Switzerland, to highlight key differences. The analysis was conducted using accident data from a 126 km section of the expressway. A preliminary assessment was performed at 10 km intervals using accident frequency data, followed by an advanced analysis at 1 km intervals using the 85th and 90th percentile accident values. The most critical sections were further examined at 100 m intervals, where accident distribution percentiles were considered to pinpoint high-risk locations. To enhance the analysis, questionnaire responses from general public, mainly drivers and road users were collected through online surveys, telephone conversations, and in- person interviews at toll booths and bus stations. These responses provided insights into real-world driving experiences, visibility challenges, and safety concerns related to sight distance. Accident-prone locations were evaluated for compliance with AASHTO sight distance and object height criteria. Crest and sag vertical curves were assessed for specific driver eye and object heights, including nighttime headlight sight distance. Passenger comfort was analyzed based on a 0.3 m/s² centripetal acceleration limit, while drainage control was reviewed for Type III vertical curves. The general appearance of vertical curves was examined using the rule-of-thumb method, and horizontal curves were assessed for lateral clearance at a 120 km/h design speed. The study found that the Southern Expressway's design meets AASHTO sight distance and object height criteria at critical locations. However, differences in stopping sight distance and vertical curve length compared to international standards were observed (0+600, 5+900, 87+300, 93+000), primarily due to variations in friction coefficients, deceleration rates, and object height assumptions. The current standard for expressways in Sri Lanka specifies an object height of 0.6 m (2 feet) for visibility assessments. Considering the height of animals crossing the road, record of animal collisions, questionnaire responses suggest that maintaining an object height of 0.15 m (6 inches) improves safety and helps reduce the risk of animal collisions.
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item: Thesis-Abstract
Introduction of partial hybrid renewable power generation system for naval complex Punewa of Sri Lanka navy
(2025) Perera, NMCJ; Witharana, S
The rapid Industrialization and Urbanization have long driven the Sri Lankan's high energy demand. As the nation continues to process, finding more cost-effective energy solutions has become essential. A clear example of this need can be seen in the Sri Lanka Navy, which faces substantial energy costs. At the Naval Complex in Punewa alone, the monthly electricity bill exceeds 3 million rupees. This significant expenditure highlights the pressing need for more efficient and affordable energy alternatives to manage rising operational costs, particularly for large-scale facilities like those run by the Navy. Comprehensive research on integrating hybrid renewable energy systems in military installations was lacking, especially in Sri Lanka. Furthermore, the possibility of mixing solar, wind, and biomass energy sources in a military context was not fully assessed by previous studies. The process comprised gathering information on the Naval Complex Punewa's energy usage trends and evaluating the region's supply of renewable energy sources. Various combinations of hybrid renewable energy were modelled using computer simulations and cost analysis. According to the report, dependency on the national grid and fossil fuels would be greatly reduced by implementing a hybrid energy system that combines solar, wind, and biomass power sources. It also highlighted how combining different renewable energy sources might reduce overall operating expenses while supplying steady electricity. To lower energy expenditures and increase energy security, the Sri Lanka Navy should invest in hybrid renewable energy systems. Adopting this strategy might also act as a model for other military locations around the country. Ultimately, installing a solar and wind energy combination with appropriate capacities was identified as the best solution for meeting the energy needs of the Punewa Naval complex. Further installing 400 kW of solar photovoltaic (PV) panels and 100 kW of wind turbine generators (WTGs) can cater to the current load.
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item: Thesis-Abstract
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item: Thesis-Abstract
Development of performance benchmark for electricity consumption in high-rise apartment buildings in Sri Lanka
(2024) Karunadeera, BRS; Witharana, S
Globally, buildings are consuming over 40% of the total global energy consumption and locally buildings are consuming over 60% of energy from the total energy consumption in Sri Lanka. Apartment buildings have become popular as residential buildings all over the world due to urbanization, increased population density and land scarcity. There are a lot of apartment buildings which are currently in operation and also there are a significant number of apartment building construction projects are currently under way in Colombo and suburban areas. The local regulatory body, Sri Lanka Sustainable Energy Authority (SLSEA) develops energy benchmark systems for different sectors in Sri Lanka. SLSEA has already published benchmarking schemes for tea, apparel, hotel sectors, commercial buildings and other industrial sectors (porcelain, tire, food, cement and concrete etc.). However, there exists a notable gap as neither residential sectors nor specifically apartment buildings have been developed with energy benchmarking standards. This gap is significant considering the rapid rise in popularity of apartment buildings throughout Colombo and its suburban areas due to urbanization, population density and land scarcity. The construction of high-rise apartment buildings has surged, driven by their popularity and commercial viability. Given these circumstances, the objective of this research study is to develop an electricity consumption benchmarking scheme specifically for high-rise apartment buildings in Sri Lanka. During the research study, the electricity consumption data for the years 2022 & 2023 were collected from 34 apartment buildings. Subsequently, the monthly electricity consumption was analyzed with respective total floor area and net floor area. Accordingly, the electricity consumption benchmarks for high-rise apartment buildings in Sri Lanka were proposed as 29.28 kWh/year/m2 per total floor area and 39.8 kWh/year/m2 per net floor area.