Browsing by Author "Dias, P"

Now showing 1 - 20 of 23

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Aesthetics and ethics in engineering: Insights from polanyi
(Springer Science+Business Media., 2011) Dias, P
Polanyi insisted that scientific knowledge was intensely personal in nature, though held with universal intent. His insights regarding the personal values of beauty and morality in science are first enunciated. These are then explored for their relevance to engineering. It is shown that the practice of engineering is also governed by aesthetics and ethics. For example, Polanyi’s three spheres of morality in science—that of the individual scientist, the scientific community and the wider society—has parallel entities in engineering. The existence of shared values in engineering is also demonstrated, in aesthetics through an example that shows convergence of practitioner opinion to solutions that represent accepted models of aesthetics; and in ethics through the recognition that many professional engineering institutions hold that the safety of the public supersedes the interests of the client. Such professional consensus can be seen as justification for studying engineering aesthetics and ethics as inter-subjective disciplines.
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Assessment of post-tsunami housing construction in Sri Lanka
Majeed, MR; Dias, P
The tsunami of26 December 2004 struck two thirds of Sri Lanka's coastline and the damage was distributed from the north down the entire eastern and southern coast and covered the west coast as far as north of Colombo. The disaster killed 35,322 people and completely destroyed more than 50,000 houses. Each district was affected by tsunami assigned a certain number of houses to be constructed. After a reasonable construction period had elapsed and the progress evaluated, a significant difference was observed between the progresses in different districts. The objective of this research was to develop a model to explain the above difference in construction progress among districts. Progress was compared among the districts and the difference was analyzed. This analysis was based on the number of houses assigned around a year after the tsunami. Four districts, namely Hambantota, Galle, Matara and Ampara were selected for further analysis. Factors that would contribute to the progress of housing construction among the districts were identified through a literature survey and interview survey. Contributing factors were short listed according to the importance and six factors were chosen as model inputs. They are; land, finance, infrastructure, raw material, human resources and political leadership / administration. These factors were assigned a common importance rating that would be the same for any district. Importance of the factors was expressed as weights, the total' adding to 1.0. Thereafter scores for each district corresponding to the availability of the identified factors were obtained from the interviewees. The sum of weighted scores for each district could then be obtained. The relationship between weighted scores and the construction progress (in terms of houses constructed and also percentage constructed/assigned) was established, and the slope and coefficient of determination of the trend lines calculated. Coefficient of determination and slope of the trend line were very high one year after the tsunami. These measures gradually reduced at two and three years after the tsunami. In conclusion it was identified that the differences in the rate of construction progress among districts was due to the level of contributing factor availability as reflected by the weighted scores for the districts. Land availability had the greatest importance among all the factors and also showed a marked difference in the four districts studied.
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Comparison of damage values used in different flood modeling studies
Randil, C; Siriwardana, C; Dias, P
Estimating the economic loss caused by a flood hazard plays a major role in decision making during disaster risk reduction activities, and such studies have been carried over some major cities of the world. This paper compares the base economic values used for building and infrastructure, depth-damage curves used and the total economic loss caused by flood hazards in five such studies carried out in Colombo, Jakarta, Manila, Bangkok and Ginosa. These original studies had the data on different formats which were adopted to this study by means of normalization. The building structural damage and the contents damage of residential, commercial and industrial building types were focused on, since the largest contributions to the direct damage arises from these categories and building types. The comparisons have shown the importance of having disaggregated building economic information for commercial and industrial buildings with similar damage curves for the same building category. Furthermore, the importance of choosing a conservative depth for flood studies is stressed. The maximum inundation depth for the studies vary from 1.8 m to 10.0 m; and the lower values may produce errors in quantifying economic losses for floods with higher return periods.
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The disciplines of engineering and history: some common ground
(Springer Science+Business Media., 2014) Dias, P
The nature of engineering and history as disciplines are explored and found to have some striking similarities, for example in the importance they place on context and practitioner involvement. They are found to be different from science, which focuses more on universal generalizations rather than on the particulars of given situations. The history of technology is paid special attention, because the discipline has developed in a way that incorporates both scientific (generalizing) and historical (context specific) characteristics. Proposals are made for giving historical studies greater space in engineering education.
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Early age cracks in concrete walls
Hettiarachchi, DS; Dias, P
During the development of construction industry, people looked forward on building their houses by Construction of a concrete structure requires a large volume of concrete. Due to the small surface area-to-volume ratio, concrete structures are often subjected to high potential of thermal cracking, caused by the heat generation from cement hydration. To reduce the thermal cracking and ensure structural integrity, a good understanding about the crack patterns in concrete elements is required. These kinds of cracks mostly occur during the early age state of concrete. Since Sri Lanka is very near to the equator, the probability of early age crack occurring is even higher. The purpose of this research is to explore the potential early age crack patterns in vertical concrete walls. Main reason for the early age cracking in vertical walls are shrinkage and thermal contraction. This research focuses on the understanding of early age thermal cracking in concrete and developing a simple method to model this phenomenal computationally. Series of boundary conditions were modelled to obtain stress distributions using walls 3m high and 4m & 8m long. Boundary conditions were imposed according to guidelines in BS8007 and wall thickness maintained as 300mm during the analysis. All the analysis was carried out using FEM commercial software Sap 2000 (V19.1). Two approaches were followed initially to identify the best method to represent the restraint conditions as per BS8007. End restraints reduced by using roller supports up to a 2.4m distance from the free edge of the wall with gradually increasing applied horizontal forces proved to be the better technique than that of using reduced E-values. The case studies yielded the following general findings that agree with the literature and field observations; (i) 4m walls can have possible vertical and horizontal cracks. (ii) 8m walls can have possible cracks approximately 2.4m away from the free edges with an inclination of approximately 45º-60º. (iii) 8m walls get the highest stress close to 2.4m from the free edges whereas the 4m walls get the highest stress at the centre. (iv) In 8m walls higher stresses are distributed over a central length whereas in 4m walls the higher stress is concentrated at the centre. (v) 4m wall with top movement can cause possible inclined cracks. (vi) 8m wall with top movement can lead to two possible dominant cracks and two minor cracks. This validation was done qualitatively using the literature and on-site observations.
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Energy content and carbon emission audit of building materials
Pooliyadde, SP; Dias, P
The main thesis examined in this research is that "the embedded energy of construction is much more significant than the operational energy for buildings in a tropical country such as Sri Lanka". All building elements (e.g. brickwall), materials (e.g. bricks) and "primitive" raw materials (e.g. clay) are placed in an aggregation-decomposition hierarchy. The process analysis carried out here basically captures most of the energy inputs associated with levels 1 and 2 in the IFIAS (1974) scheme, and accounts for around 90% of the embedded energy in a product. These calculations are based on Tonnes of Oil Equivalent (TOE). The data required to estimate these embedded energies were collected from building materials manufacturers. A computerised database was implemented using a relational database management system. This can be used to represent and calculate the embedded energies and carbon coefficients of building materials and elements that are hierarchically arranged. It can also handle multiple sources of data and perform calculations to give the average, maximum and minimum embedded energies, which are also classified according to fuel type and process stage. Though the analysis was done assuming that the final building is located in the City of Colombo, these database values can be used, with some caution, for buildings even outside the Colombo City or District. The embedded energy requirements were also calculated on the basis of the lowest quality energy (bio-equivalent energy), in addition to the more conventional basis of TOE. According to energy quality calculations carried out (based on efficiency considerations), 1GJ of energy from electricity is equivalent to 5 GJ of biomass energy, 1 GJ of fossil fuel energy is equivalent to 1.8 GJ of biomass energy and 1 GJ of electrical energy is equivalent to 2.78 GJ of fossil fuel energy. It is seen that the price per unit of biomass energy based on the actual prices of products is around one third of the actual price per unit of biomass energy. For fossil fuel and electricity on the other hand, the actual prices of products are much higher than the actual prices of the energy sources used for their production. In order to minimise adverse energy effects and to give a beneficial effect to halting global warming, policy measures to promote timber products are desirable. It is also seen that though materials which use timber fuels (e.g. bricks and tiles) consume more energy, the use of timber fuels is more competitive when compared on a bio-equivalent unit basis. Furthermore, with respect to carbon emissions, wood fuels are considered to be self sustaining. The use of timber, whether as a construction material or a fuel, will require properly planned re-forestation strategies. The energy contribution from walls for a typical two storey house is from 10 - 44%; for a single storey house it is from 29 - 49%. The contribution from roofs for the two storey house is from 4 - 7%, whereas it is 8 - 16% for the single storey house. The contribution from windows is 0.6 - 3% for the single storey house and 0.2 - 4.5% for the two storey. house. The contribution from the floor slab for the two storey house is 6 - 7%. The above ranges are a result of the difference of the between the use of low and high energy materials. The ratio between total embedded energy and annual operational energy for the buildings selected lies between 14 to 35 for the houses while for an office building with air conditioning loading it is 5. Though air conditioning has a large contribution towards the annual operational energy of a building, the total number of air conditioned buildings are small for a developing country such as Sri Lanka. Nevertheless, the results of the analysis show that the focus of energy efficient designs for buildings with air conditioning has to be on the operational energy. On the other hand, for houses, which are largely not air conditioned, the way to promote efficiency is by reducing the embedded energy through the appropriate choice of building materials. This is borne out not only by the high ratio of construction to operational energy ratio obtained, but also by the fact that the ratios for houses with low energy materials is almost half those for the houses with high energy materials. Key Words : Embedded Energy, Process Analysis, Building Materials, Carbon Emissions, Energy Database
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Engineering surveys of Sri Lankan schools exposed to tsunami
(2023) Cels, J; Rossetto, T; Dias, P; Thamboo, J; Wijesundara, K; Baiguera, M; Del Zoppo, M
The 2004 Indian Ocean tsunami affected 5% of Sri Lanka’s schools, severely damaging 108 and destroying 74. The catastrophe highlighted the critical role of schools in providing educational continuity during community recovery. Sri Lanka has since rehabilitated and rebuilt most of the destroyed schools along the coastline. However, there is a limited understanding of current levels of school exposure to tsunami. This hampers preparedness and risk reduction interventions that can improve community and educational tsunami resilience. This paper presents a multi-disciplinary school exposure database relevant to both vulnerability and loss modelling. The repository includes data on 38 schools and 86 classroom buildings, surveyed across the coastal districts of Ampara, Batticaloa and Galle in Sri Lanka, which were heavily affected by the 2004 tsunami. A new engineering rapid visual survey tool is presented that was used to conduct the physical assessment of schools for the exposure repository. School damage mechanisms observed in past tsunami inform the survey forms, which are designed to capture information at both school compound and building levels. The tsunami engineering survey tools are universally applicable for the visual assessment of schools exposed to tsunami. The surveys show that most Sri Lankan school buildings can be classified into three building archetypes. This means that future risk assessments can be conducted considering a small number of index buildings that are based on these archetypes with differing partition arrangements and structural health conditions. The surveys also raise three significant concerns. Firstly, most schools affected by the 2004 tsunami remain in the same exposed locations without any consideration for tsunami design or strengthening provisions. Secondly, Sri Lankan schools are fragile to tsunami loading and many of the schools in the Galle district suffer from severe corrosion, which will further affect their tsunami vulnerability. Thirdly, schools do not appear prepared for tsunami, and do not have adequate tsunami warnings nor evacuation protocols in place. These observations raise the urgent need to mitigate tsunami risk, including a holistic plan for tsunami retrofitting and for interventions to improve the tsunami preparedness of schools in Sri Lanka.
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Factors that affect the performance of students in Cambridge GCE(Ordinary Level) Mathematics
(2015-01-06) Jayasinghe, CDS; Dias, P
The purpose of this study was to identify the factors that affect student performance in Cambridge GCE (Ordinary Level) Mathematics. The four factors selected for the study dealt with students, teachers, school management and the parents. A group of 57 students studying in two classes of a private school and sitting the Cambridge GCE (Ordinary Level) Examination in the year 2011 formed the main source of data for this study. The data needed from this source were collected through a questionnaire administered to the students. In addition to the above, the questionnaire method was used to collect data from the three other sources namely teachers who taught Mathematics to these students, the school management, and the parents of the student group under concerned. Independent t-test, Mann-Whitney test, one way ANOVA, Tukey’s comparison procedure and Kruskal-Wallis test were used to analyse the data so collected. All the tests were conducted at 5% level of significance. Analysis of student data revealed that the students who were in the habit of using public library than the school library, the students learning slowly or moderately with more grasping power than others who learned speedily, students who enjoy learning Mathematics performing better in the examinations, the students considering the teaching style in line with their preference and the students either having no opinion or denying any encouragement from the management. An analysis of data collected from teachers identified that for better student performance in Mathematics both students and teachers should derive pleasure from their learning and teaching task respectively. Provision of adequate time in the time table for the subjects under concern, use of modern methods of teaching and receiving due support from the school management and the parents are other main factors found to be of importance. The study also found that it was the responsibility of the school management to stick to the punctuality considerations, and take timely action to hold school tests and provide the needed learning-teaching materials. The data collected from the school management revealed that they paid high priority for students and teachers punctuality and less priority for school tests. Provision of curricular material in the class room was also identified as another priority area. In addition to the school related factors that contribute to the success of student learning the parents also have a part to play. In this respect they should ensure regular school attendance of their children, make arrangements to check their homework and provide suitable home environment conducive to learning. Moreover, parents have to extend their support to promote Mathematics-related activities undertaken by the school and meet teachers regularly to find out the strengths and weaknesses of their children with a view to taking suitable action to overcome any learning difficulties encountered by their children.
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Height limits for reinforced concrete wall-slab residential buildings
(2015-09-17) De Silva, AKTV; Dias, P
It is common in urban areas for medium rise residential buildings to be constructed with a scarcity of land. With rapid urban growth in developing countries like Sri Lanka, it is crucial that low income families are provided with better living conditions. Construction of residential buildings with higher number of stories for low income families in Colombo has already started and further plans for constructing more buildings are likely. In order to eliminate the space taken by columns and beams in vertical and horizontal spaces in each floor and to reduce the time spent for partition wall construction, reinforced concrete wall-slab structures are arguably the best structural form for residential buildings. In this research, the wall thickness requirements in several codes of practices were analyzed to select the minimum possible wall thickness with respect to durability and fire requirements as well as practical feasibility. Three building layouts were generated with approximately similar floor areas, wall densities and number of stories but with different aspect ratios and modeled using computer software. By using the maximum stress figures obtained from the analysis, calculations were made to predict the maximum number of stories achievable with selected wall thicknesses in each building. Further a seismic analysis was done for all three buildings to compare their behavior under an earthquake. Comparing several codes of practices and considering practical feasibility, the minimum wall thickness for double layered reinforced concrete walls was obtained as 180mm and for single layered reinforced concrete walls as 130mm. The maximum stories achievable in buildings with aspect ratios of 2, 1.15 and 6.7 ranged from 16 to 8, 16 to 8 and 14 to 8 respectively, depending on its grid spacing (i.e. whether 3m or 6m) and wall thickness (i.e. whether 180mm or 130mm). Buildings having aspect ratios of 2 and 1.15 with 12 stories showed sufficient capacity under seismic action too.
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Identifying the factors affecting the quality level of services in enterprise resource planning consultancy services - a case study on post implementation support
(2023) Wickramarachchi, AP; Dias, P
Businesses commonly seek support from Enterprise Resource Planning (ERP) consultancy firms to evade the risk of ERP implementation failure. These consultants are involved in both implementation and post implementation phases. The aim of this study is to identify the factors that impact service quality in post implementation ERP support. A structured questionnaire with 46 questions was used to collect the data from 87 consultants working in a consultancy firm. The questionnaire consisted of 8 general questions related to the background of the consultant and 9 independent variables (Knowledge of the Consultant, Job satisfaction, Clear communication of the Service Level Agreements (SLAs), Internal communication, Project Management techniques, Customer culture, Customer knowledge, Clear communication of the incident, X first level support strength within the customer organization) and 4 dependent variables (Responsiveness, Reliability, Goodwill, Escalations) were considered. The 9 independent variables were further segregated in to two factors as internal (Consultant Knowledge, Job satisfaction, Clear communication of the Service Level Agreements (SLAs), Internal communication, Project Management techniques) and external factors (Customer culture, Customer knowledge, Clear communication of the incident, First level support strength within the organization).Correlations among independent and dependent variables were studied and it was identified that each of the 4 dependent variables had a significant correlation between each of the independent variable identified except for the correlation between Responsiveness and Knowledge level of the consultant variables. From the 9 independent variable 2 internal independent variables (Knowledge of the consultant and Clear communication of the SLA s) and 3 external independent variables (Customer knowledge, Clear communication of the incident, first level support strength) were identified using Stepwise Regression analysis to explain the variability of the dependent variables (Responsiveness, Reliability, Goodwill, Escalations). Therefore, it can be concluded that both internal and external factors are important to maintain the service quality..
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Influence of exterior infill walls on the performance of RC frames under tsunami loads: Case study of school buildings in Sri Lanka
(Elsevier, 2021) Zoppo, MD; Wijesundara, K; Rossetto, T; Dias, P; Baiguera, M; Ludovico, MD; Thamboo, J; Prota, A
This paper assesses the structural performance of RC frame buildings subjected to tsunami-induced loads, accounting for the influence of exterior masonry infill walls on the overall structural performance. Both the in-plane and out-of-plane contributions of masonry infill walls are considered in the analysis. To illustrate the importance of accounting for exterior infill walls in the response of structures to tsunami, two case study buildings are considered and modelled in 3D. The first case study is a typical two-storey school building in Sri Lanka, and the second is a modified version of this design configuration proposed in Sri Lanka after the 2004 Indian Ocean Tsunami to provide more redundancy against scour. Through these case studies, the effect of the non-uniform distribution of infill walls in the building and their failure (or “breakaway”) on building performance is considered. The building performance is characterized by a number of response parameters (i.e., first yielding, development of two hinges, and shear failure in ground floor columns). The paper shows that the in-plane behaviour of exterior infill walls increases the flexural capacity and lateral stiffness of the structure, as would be expected. However, it also shows that an assumption of non-breakaway infill walls consistently leads to premature structural failure mechanisms, associated with the concentration of drag forces on seaward columns only. The results demonstrate that a good estimation of the location and occurrence of shear failure in structural elements can only be achieved by explicitly considering the out-of-plane behaviour and failure of exterior infill walls during an incremental tsunami load analysis. Finally, the Froude number assumed for the analysis is seen to strongly affect the performance of both structural and non-structural components, highlighting the importance of choosing realistic tsunami properties to perform a reliable capacity assessment.
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Intelligent buildings for intelligent people A concept
(2013-11-19) De Silva, S; Dias, P
The past decade has seen unparalleled evolution in the field of Materials engineering. Largely due to the unique properties seen in materials in the nanoscale relative to their macroscopic counterparts, nanomaterials as an example can be used to enhance tensile strength, insulation and are biomimicable. These properties combined with integrated structural monitoring and diagnostics systems are set to revolutionize the construction industry. Current research shows the inclusion of self healing properties, bringing these endeavors full cycle. Structural integrity is a key facet of building maintenance which historically has been evaluated on the basis of empirical studies stemming from lifecycle analysis of the concerned structure. The associated costs, lead times and lost revenue due to these activities can be mitigated by using materials which are engineered to report the parameters of concern to building monitoring systems. These systems can be the resultant of nanocomposite materials which are self organizing in nature, in turn forming interrogation capable grids. Dielectric and complex impedance measurements of these grids will be sampled through an analog to digital conversion interface linking the captured data on to the building management system. Alerts can be issued in real time when material boundaries are crossed, indicating impeding structural changes. Constants associated with the nanocomposite materials will set the thresholds for the alerts. The captured raw data would have the ability to monitor parameters such as vibration, stress/stain (piezoelectric materials) and thermal gradients (temperature coefficient of complex impedance). Furthermore, materials such as TiO2 facilitate photocatalysis, where the free radicals can be used for the oxidization of organic matter resulting in self cleaning surfaces. Anatase titanium dioxide can also be used in the form of a composite addition to cement for Bio mimicking structures to be used to offset our carbon footprint. Although yields of such activities remain low, the research too is in its infancy. By monitoring the redox reactions of these materials in the form mentioned above, it will be possible to observe the conversion efficiency as live “heat map”, resulting in much needed empirical data. Reportedly, the use of TiO2 has been used to control the growth of biological matter. As deterioration of structures due to biological matter is immense, these properties will allow for the control and monitoring of the design and environmental parameters which facilitate their growth. Macroscopically the construction industry is poised to benefit greatly by these immediate changes that nanotechnology has brought to the materials engineering. Resultant structures would encompass the low carbon footprint which is expected and sought after in the current climate as well as the economic and safety benefits inherent of such activities. This paper reviews a range of concepts and technologies capable of harmonizing built environment and the state of the art in monitoring and energy capture.
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Multi-criteria assessments for environmental sustainability of buildings
Chandrathilake, SRMSR; Dias, P
In the last couple of decades there has arisen a crowded toolbox of quantitative methods used to assess construction sustainability. The evolution of the assessment systems shows the interest in quantifying sustainability with a range of very specific indicators. The majority of the existing sustainability assessment methods for buildings evaluate performance of buildings for a selected set of domains, with a lot of commonality. This study focuses on the building sector and as the first step relevant domains were identified though comprehensive analysis of available assessment systems. Site, energy efficiency, water efficiency, material, indoor environmental quality and waste and pollution are the identified domain for the study. Secondly, aspects of (criteria for) the selected domains were identified and the relative importance of the domains and aspects was established by an expert survey. Thirdly the overall domain weights were compared with those assigned by other rating systems, originating from different countries to find the correlation which can demonstrate the influence of national contexts for relative weights in rating systems. The fourth step is to analyse the applicability of continuous functions to assess the sustainability in contrast to step functions to facilitate ‘assessment’ rather ‘rating’ of buildings. Fourth aspect of this research is to establish the dependencies and influences between indicator scores within domains. The matrix representation was used to handle these direct and indirect influences. Finally the research focused on optimisation techniques that can be used to handle tradeoffs between indicator scores and to arrive at acceptable indicator combinations with optimised environmental sustainable scores for a given building. It was found that in the building hierarchy the “system” level is the most important, having over fifty percent of overall weight. In the building lifecycle, the “operation” stage is the most important phase. There is also strong coupling between the operation stage and system level. Good correlation was found between national statistics and the weights, demonstrating that national contexts influence the relative weights in rating systems. The outcome of the dependency evaluation shows that there are considerable dependencies between indicator scores. It was found that the proposed optimisation technique is truly useful to arrive at planning strategies that yield high environmental sustainability scores for buildings while accounting for negative dependencies.
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Multidisciplinary product models for buildings
Kodagoda, GN; Dias, P
A building is an entity that is multidisciplinary by nature. Traditionally drawings have been used as the medium of communication between the various disciplines. With the advent of microcomputers, professionals from different disciplines have made use of computer software for their work. One of the major obstacles has been the exchange of data between such software. This thesis presents a practical product model of a building which addresses these issues. It is based on an object oriented design. A primitive composite scheme is used to reduce the complexity of the model and to make it flexible. Two object hierarchies are presented. The building elements hierarchy consists of architectural, structural and service elements of a building. The multidisciplinary attributes of a building are captured by the primitive object hierarchies. Geometry however is implemented directly ill the building elements and not as a primitive, as geometry is seen as a fundamental and integrating property of all aspects of a building. The primitive properties can be attached dynamically to the building elements, thus creating composites. Primitive objects could be declared globally and shared among several building elements to improve efficiency. They could also be defined locally to individual building elements. Three generic classes junctions, paths and outlets were proposed to represent service type elements. This, allows a diverse range of services to be accommodated without complicating the model. All building elements were represented as lines, and subsequently fleshed out according to their cross sectional dimensions. Wherever possible local geometry was used (c.g. for contained elements such as doors and windows with respect to the containing wall). The semantic relations "components", "cornponcnt_of", "parts", "part_of" and "connected" were used to define relationships between instances of building elements. A software called PROMOD was developed based on the proposed product model. The implementation was carried out in Delphi (an object oriented programming environment). The building is drawn using the 20 graphical input module of PROMOD. The input module automatically establishes the various relationships between the elements. Using PROMOD, different 20 views of the building can be generated. Data entered into the product model was successfully exported to AutoCAD, to generate 3D views, and also to PROKON, to carry out structural analysis. III addition, the possibility of using the product model as a rich database was explored. It is shown that the semantic data stored within the model is sufficient to answer a varied range of queries (including cross disciplinary ones). The thesis demonstrates the application of the model using the example of a two storey office cum residential reinforced concrete frame building with masonry infill walls. Key Words: Product Models, Object Oriented, Services, Buildings, Structural, CAD
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A New relative risk Index for hospitals exposed to Tsunami
(Frontiers Media S.A., 2021) Baiguera, M; Rossetto, T; Palomino, J; Dias, P; Lopez-Querol, S; Siriwardana, C; Hasalanka, H; Ioannou, I; Robinson, D
The failure of hospitals in recent tsunami have caused extensive social and economic losses. A simple but quantitative approach is required to assess the resilience of healthcare systems to tsunami, which relates not only to hospital building integrity, but also to maintaining hospital functionality. This paper proposes a new tsunami relative risk index (TRRI) that quantifies the impact of tsunami on critical units, (e.g. Intensive Care Unit, Maternity Ward, etc) in individual hospitals, as well as the impact on service provision across a network of hospitals. A survey form is specifically developed for collecting of field data on hospitals for the TRRI evaluation. In its current form TRRI is designed for hospital buildings of reinforced concrete construction, as these are the building types most commonly used worldwide for housing critical units. The TRRI is demonstrated through an application to three hospitals located along the southern coast of Sri Lanka. The TRRI is evaluated for three potential tsunami inundation events and is shown to be able to identify issues with both the building and functional aspects of hospital critical units. Three “what-if” intervention scenarios are presented and their effect on the TRRI is assessed. Through this exercise, it is shown that the TRRI can be used by decision makers to simply explore the effectiveness of individual and combined interventions in improving the tsunami resilience of healthcare provision across the hospital system.
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Possible influences of covid-19 on infrastructure
(IEEE, 2023-12-09) Wijekoon, U; Dias, P; Abeysooriya, R; Adikariwattage, V; Hemachandra, K
During the coronavirus (COVID-19) outbreak, there was a sharp rise in the number of persons working from home (WFH), which eventually became the "new normal". The aim of this study was to fill the gap in detailed quantitative knowledge regarding space and travel savings as a result of WFH, albeit via a specific case study. The main objectives were to (i) Identify relevant issues via a systematic literature review; (ii) Compute the office space and fuel savings accrued when using hybrid working techniques; (iii) Explore employee preferences and attitudes towards WFH after categorizing the employees and (iv) Seek correlations between responses from the various employee responses. The findings show that, considering the reduced number of days of office space usage, 59% of office area can be saved from WFH. The employees' fuel savings were calculated for five separate groups of staff. The fuel savings ranged from 52% to 69% across the groups. The data indicated that employees are happy to work from home in general, and that there is potential to save office space. There is also some evidence that existing social differences across the workforce may have widened.
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Post-december 2004 tsunami reconstruction in Sri Lanka and its potential impacts on future vulnerability
(Earthquake Engineering Research Institute, 2006) Khazai, B; Franco, G; Ingram, JC; del Rio, CR; Dias, P; Dissanayake, P; Chandratilake, R; Kanna, SJ
The 26 December 2004 tsunami displaced more than 500,000 people and killed an estimated 31,000 in Sri Lanka. Damage was not uniform, often reflecting distinct patterns of social, infrastructural, and ecological vulnerability. Severely affected populations tended to be poorer, to live in fragile structures, and to be more exposed to the tsunami as a result of prior environmental degradation in the coastal zone. The massive reconstruction effort may further decrease the resilience of rural communities by degrading the natural environment that sustains their livelihoods. A sustainable reconstruction approach must therefore consider long-term solutions that increase community resilience by fostering socioeconomic, infrastructural, and environmental progress. A reconnaissance team monitored the initial recovery stages and identified mechanisms in supporting research on reducing the long-term vulnerability of human settlements and ecosystems to future environmental hazards.
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Rapid risk assessment of Sri Lankan school buildings against tsunamis
(IEEE, 2022-07) Nawanandana, C; Dias, P; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Rapid assessment of building vulnerability and risk is very useful, especially if based on sound engineering principles as opposed to expert opinion alone. A tsunami relative risk index (TRRI) has recently been proposed for hospital buildings based on such an approach. This study extends the concept to reinforced concrete school buildings. Two typical plan forms of school buildings were explored, each of two and three storey height. The criterion for overall structural failure was the shear capacity of columns; for scour, the number of footings undermined; and for debris impact, the shear capacity of corner columns. Of the parameters explored, the inundation depth and flow velocity were found to have the greatest influence on TRRI, while building type, building height and flow direction had much smaller influence. Debris impact was the governing risk at low inundation depths (around 1m), with scour at medium depths (around 3m) and overall structural shear failure at higher depths (around 5m).
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Rapid seismic visual screen method for masonry infilled reinforced concrete framed buildings: Application to typical Sri Lankan school buildings
(Elsevier, 2023) Sathurshan, M; Thamboo, J; Mallikarachchi, C; Wijesundara, K; Dias, P
Seismic rapid visual screening (RVS) methods are used when a large stock of structures is to be evaluated for seismic risk. Although several RVS methods are available, applications of those methods to appraise the seismic risk of reinforced concrete framed (RC) buildings with irregularities in masonry infill walls (MIWs) are limited. School buildings constructed in Sri Lanka are built with certain RC frame typologies; however, they vary in terms of MIW arrangements used. Therefore, a new RVS method is proposed to evaluate the seismic risk of masonry infilled reinforced concrete (RC-MIW) buildings, particularly for the typical RC-MIW school buildings in Sri Lanka. The proposed RVS method incorporates irregularities of MIW arrangements in the typical RC buildings, the attributes of which are not well accounted in the available RVS methods. The vulnerability attributes such as short column and soft storey effects, arise due to the irregularities of MIW arrangements in the buildings, are explicitly incorporated in the proposed RVS method. The FEMA P-154 guidelines were followed to develop basic scores, score modifiers and minimum scores in the proposed RVS method. For that purpose, seismic performances of RC-MIW schools with various MIW irregularities were numerically analysed. The effectiveness of the proposed RVS method is compared with the existing RVS methods to evaluate the seismic risk of typical RC-MIW school buildings in Sri Lanka. It is shown that the proposed RVS method is capable of capturing the seismic risks of such typical RC-MIW Sri Lankan school buildings
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Representation of a reinforced concrete design code as an object oriented mode
Fernando, WJBS; Dias, P
Design standards comprise many knowledge types such as text, rules, equations, tables, graphs and figures. The attempt is to encode the standard without distorting the format of the standard, i.e. to represent the standard clauses and tables in the same format as in the standard. This effort will facilitate changes to the standards without much variation to the programme code. This thesis presents a framework to model standards using the Object Oriented Programming paradigm. It also presents the concept of a common interface, i.e. to accommodate several design standards for reinforced concrete design in one module; however, implementation is carried out only for BS8110. The programme uses an inferencing mechanism for execution, which is a similar method of execution to that of a standard's user; it is not a hard coded structured programme. This is a novel concept when compared to the available software for reinforced concrete design. The literature review investigates the structure of typical standards and the available standards processing technique such as Predicate Logic, Decision Tables, Production Systems and Semantic Networks before choosing Object Oriented programming as the preferred one. The review also compares both the provisions and design outputs of several reinforced concrete standards. The Common Interface for Design Standards (COIDS) has three mam modules (or models), namely the Product Model, Standards Model and Interaction Model. The Product Model handles the product data, e.g. Frame Data. The Standards Model handles the standards data, i.e. it contains all the knowledge in a standard. The Interaction Model handles the data exchange between the user,-COIDS objects and external software. It transfers data from the COIDS to external analysis software and maps analysis output files to COIDS. An Object Oriented Shell called KAPPA was used to develop the object oriented model.