Civil Engineering Research for Industry Symposium

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Analysis of settlement monitoring data to assess the state of primary and secondary consolidation of soft organic soil deposits
(Department of Civil Engineering, University of Moratuwa, 2012-12) Premalal, RPDS; Jayasinghe, TWASL; Indrachapa, KRTH; Thilakasiri, HS; Nawagamuwa, U; De SIlva, LIN
Organic soil deposits under road embankments may cause consolidation settlement problems during the serviceability stage. It is not feasible to design road traces on such soil deposits using the traditionally used most unfavourable ground conditions. Instead the most probable ground conditions are used in the initial design and this approach is referred to as the observational approach. The risks associated with using most probable soil properties are managed by reviewing the initial design through the analysis of the observational data obtained during the construction stage. In this regards, analysis tools to assess the stability of the embankment during construction stage and the estimation of the degree of consolidation during ground improvement phase are extremely important. Even though there are large number of analytical methods available to use for the data analysis, not much research is done to identify the tools relevant to the organic soft soils found in Sri Lanka. This research is aimed at investigation of the analytical tools that can be used in the analysis of settlement monitoring data obtained during the implementation of the observational approach for construction of the road embankments over the soft soil deposits in Sri Lanka.
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Applicability of HCM 2000 to determine the level of service in urban arterial roads, Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2012-12) Mampearachchi, WK; Jayasuriya, WWC; Senaratne, SAMANI; Nawagamuwa, U; de Silva, LIN
T16 obJective of this research is to identify the applicability of Highway Capacity Manual (HCM) to determine the Level of service in urban minor arterial roads in Sri Lanka. HCM has been developed by the transport research board, USA. Currently most of the local road eve opment agencies use HCM for capacity analysis of roads. There have been no researches carried out to identify the applicability of HCM to the Sri Lankan condition. To depict the quality of service of the roads quantitative measures of a traffic stream are required. Level of Service (LOS) is a quality measure describing operational conditions within a traffic stream, generally in terms of service measures such as speed and travel time, freedom to maneuver, traffic interruptions and comfort. Six LOS are defined based on service flow rates of roads. Letters designate each level from A to F with LOS A representing the best operating conditions and LOS F the worst. Though the local roads have acceptable LOS, the results obtained from both HCM 2000 andl986 have not reflected it It is required to identify the factors which affect the LOS. For that a sample of two way - two lane roads were selected. For the selected sample flow vs. density curves have been developed by considering traffic data and speed survey data. Based on the literature findings and data collected from the field, six LOS for the urban minor arterial roads have been defined.
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An aquifer characteristic analysis for identifying ground water resource development alternatives in the wet zone of Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2011) Mayooran, S; Manarathna, SP; Gogulan, N; Rajapakse, RLHL; Ratnayake, N
A proper management system for groundwater resources in the wet zone of Sri Lanka is crucially needed to avoid further exploitation of the resource leading to deterioration of groundwater quality. This research study mainly targets on the assessment of groundwater in the wet zone of Sri Lanka by means of collecting and analysing available groundwater pumping and aquifer characteristic data towards the identification of best management practices. The pumping test data are collected from well locations in Kalutara district and transmissivity values are estimated using both Theis and Cooper Jacob methods. The estimated transmissivity values are used to identify the spatial variation of transmissivity. It is recognized that there is no particular pattern identifiable in the spatial distribution of estimated transmissivity values, however, with the limited data set available. The observation is in line with the fact that there exists significant groundwater anisotropy and heterogeneity even within the same locality or within a single distinct aquifer system. The transmissivity values are further analysed using statistical testing and Krasny's classification system, transforming the data set into log distribution and assigning an index value to identify best management practices for selecting suitable locations for both local water supply schemes and landfills. The places with positive anomalies are very suitable for locating local water supply schemes, and the places with negative anomalies are best to have toxic waste disposal sites or landfills.
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Assessing the cracks developed in Dematamal Viharaya, Butthala
(Department of Civil Engineering, University of Moratuwa, Sri Lanka., 2011-12) Jayasinghe, MTR; Paskaran, S; Perera, TM; Kumara, D; Ratnayake, N
Stupas of Sri Lanka stand as proud examples for the engineering excellence of ancient Sri Lanka. Dematamal Viharaya at Butthala is one of the oldest stupas in Sri Lanka built in the 2nd Century BC which is a, 19m tall non-plastered brick structure. This stupa has developed cracks since 1998. Cracks have initiated from the pesawalalu and propagate to the top of the dome. The research covered in this report is aimed at the identification of the A comprehensive study was carried out to identify the possible causes for the cracks which may be due to self weight and shape of the stupa, expansive nature of soil, arch action induced due to separation of old and modern masonry. Experiments were done to assess the expansive nature of the soil and a Finite element analysis was carried out using the Finite element software SAP2000. The results revealed that the possible cause may be the arch action induced due to separation of old and modern masonry.
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Bond performance of CFRP strengthened concrete subjected to fire
(2011-12) Ranasinghe, RATM; Jinadasa, DVLR; Srilal, HPS; Gamage, JCPH; Ratnayake, N
CFRP (Carbon Fibre Reinforce Polymer) strengthening system has recently emerged as a practical alternative for the flexural strengthening of reinforced concrete structures because of its efficiency in terms of structural performances, costs, labour and time savings. While CFRP is widely used in bridge construction, it can also be taken advantage of for strengthening concrete members such as beams, columns and slabs. Even though structural engineers are interested in using CFRP for the strengthening work of concrete members in buildings, always hesitation occurs due to lack of knowledge of its fire performance. Therefore it is essential to assess and develop the needed information on fire resistance of CFRP strengthened concrete structural members. The epoxy adhesive used to create the bond is known to be very sensitive totemperature and its mechanical properties deteriorate rapidly with exposure toelevated temperature. The CFRP sheet or plate itself cannot provide sufficient insulation to the composite system. Therefore, application of a suitable insulation onto the CFRP sheet is important, especially in the application to buildings.In this study the behaviour of insulated CFRP/concrete members subjected to standard fire condition is explored. A finite element model, developed by using commercially available software ANSYS was used to simulate the thermal behaviour of the insulated composite structure.
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Cement stabilized rammed earth for wall junctions of two storey houses
(Department of Civil Engineering, University of Moratuwa, 2011) Kandamby, T; Jayasinghe, C; Ratnayake, N
Today the whole world is faced with environmental issues due to unsustainable use of natural resources, especially for construction activities. Finding alternative materials and methods is vital to minimize the impacts and protect the environment from natural disasters. Further increase in demand as well as the rising cost of building materials in Sri Lanka has compelled the general public to use alternative materials. Rammed earth is an ancient technology that has been used in all part of the world to construct different types of civil engineering structures such as buildings, houses, roads and dams. In the current research, rammed earth technology was developed as a means of stabilizing soil with cement to produce an alternative material for building houses due to its valuable characteristics such as affordability, environment friendly, comfort, strong and durability. The mouldis placed in between two columns made out of compressed stabilized earth blocks (CSEB) which were manufactured as per the newly established Sri Lanka Standards. It was found that performances of CSEB columns with CSRE walls were not very successful due to differential shrinkage. Further, this study revealed that the development of wall junctions is necessary to satisfy* the design aspects and to avoid the present construction issues in order to popularize this technology. "L" and "T" junctions made with CSRE and timber mouldswas introduced as an alternative method for making wall junctions to overcome the above-mentioned issues. Method of constructing CSRE walls with CSRE junctions would encourage people to accept this technology* because it is economical and simple.
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Civil Engineering Research for Industry Symposium 2011 (Pre Text)
(Department of Civil Engineering, 2011-12) Ratnayake, N
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Civil Engineering Research for Industry Symposium 2012 (Pre Text)
(Department of Civil Engineering, University of Moratuwa, 2012) de Silva, LIN
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Developing psychological contract to sustain construction industry workforce: a review of literature
(Department of Civil Engineering, University of Moratuwa, 2011-12) Chandradasa, V; Ekanayake, L; Ratnayake, N
Sri Lankan Construction Industry suffers due to shortage of construction labour though the country records an unemployment rate above four percent. About seven percent of the physical production workforce in the industry is above its retirement age and they still have to struggle due tounavailability of effective and lifelong social security systems(VVijewickreme and Ekanayake, 2010). For the same reason,the industry finds it difficult to attract youth and retain experienced people within the construction industry. Inability of the construction industry to retain its experienced workforce is one of the main barriers to effective technology transfer (VVeerasinghe and Ekanayake, 2011). Hence, the requirement of good human resource management practices in making the existing employees more productive and retaining them has become important. It is found that satisfied employees are those who enjoy coining to work with an attitude to excel and exhibit a sense of pride and ownership in their work (Healthcare Registration, 2007). The key issue in the formation of this employee-employer relationship is the emergence of psychological contract (Barnard, 1973). Psychological contract emerges when an individual believes that he/she owes the employer certain contributions as hard work and loyalty, in return for certain inducements as high pay, job security etc. (Rousseau, 1990).This paper discusses the theoretical background and two models of psychological contract which can be related to the physical production workers of the construction industry. This paper is prepared based on an initial literature survey on an ongoing PhD-research work in the department of Civil Engineering.
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Effect of relict joints in rain induced slope failures in residual soil
(Department of Civil Engineering, University of Moratuwa, 2011-12) Tharmalingam, N; Lakshamana, NWH; Kumarasinghe, RDTB; Kulathilaka, SAS; Ratnayake, N
Rain inducted slope failures are a common geotechnical hazard in the most parts of the world. particularly in the tropical reagon, which are covered with residual, soil, the temporal frequency of rainfall inducted slope failures is very high. These problems are encountered frequently in the construction of highway where very high cuts are made in the slopes. Residual soils are formed due to weathering of rocks and the joints remain as relict joint even after the weathering process. The residual soils are heterogeneous due to variable weathering of the jointed mass rock. Generally the ground water table is low during the dry season and these soils are in an unsaturated state with negative pore water pressure above the water table. As a result of infiltration of rain water, the matric suction will be distroued and ground water table will rise. Relict joints present in the system will further complicate the pattern of infiltration. Changes in the pore pressure regime due to infiltration and its effect on safety was studied in a previous research. The objective of this research is to investigate the effects of different systems of relict joints in the infiltration and stability. This aspect was studied in this research using SEEPW, SLOPEW software.
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Effects of global warming on landslide frequencies in Ratnapura District, Sri Lanka - 2011
(Department of Civil Engineering, University of Moratuwa, 2011-12) Rathnaweera, TD; Nawagamuwa, UP; Ratnayake, N
Unpredictable variability of rainfall patterns could probably be due to global climate changes with the increased frequency of extream whether events. Infact, rainfall is the most relevant factor for the triggering of both shallow and deep - seated landslides in Sri Lanka. Landslides related to heavy rainfall cause widespread property damage and occasional loss of lives. in recent years, number of rain-induced landslides have been increased in the Ratnapura district due to heavy rainfall. One of the most critical concerns in landslide study at the moment is the potential link between climate change and the frequancis of mass movement occurrences. In this research and overall study of the climate change on landslide frequencies in Ratnapura, distric is done by analysis the trend of the rainfall and temperature variation patterns.
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Evaluation of soil liquefaction in Sri Lanka - a dynamic approach using geotechnical investigation data
(Department of Civil Engineering, University of Moratuwa, Sri Lanka., 2012-12) Kumarasiri, C; de Silva, N; Abayakoon, S; Nawagamuwa, U; De Silva, LIN
Soil Liquefaction is a process, where granular soils below the ground water table temporary lose its strength and behaved as a viscous fluid rather than a solid. The porewater pressure is suddenly increased during an earthquake due to the cyclic loading. The increased porewater pressure is forced the soil particles to suspend in water. As a result, the buildings, utility services, natural substances and other structures are collapsed causing severe damage to the people and the nature. In Sri Lanka, it is rare to find the historical data of liquefaction or related incidents. Recent studies demonstrated that there is a potential for liquefaction in some places of the island. It could be evaluated by using the basic geotechnical investigation data, according to the simplified procedure proposed by Seed and Idriss (1971). This paper is intended to evaluate the liquefaction potential in Sri Lanka by identifying the liquefiable layer thickness, using an extensive geotechnical investigation data base. As per the analysis 384 locations were identified as susceptible for liquefaction with various layer thicknesses out of 3282 locations analysed. Further, the analysis has extended for varied ground water table.
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Evaporative cooling for occupational health in tropical climates
(Department of Civil Engineering, University of Moratuwa, 2011-12) Arandara, KP; Jayasinghe, C; Jayasinghe, MTR; Ratnayake, N
Occupational health is a cross disciplinary area concerned with protecting the health of people engaged in work or employment. If is increasingly becoming a serious concern for industries and companies to safeguard the well-being of their employees. When address the physical hazards under occupation health, provision of thermal comfort is very important, especially to avoid hyperthermia condition which could be a vital issue in tropical climates. Hlence, there should be a HVAC system like Evaporative cooling which has best performances in terms of thermal comfort as well as the occupational health. Evaporative cooling is a best alternative for providing thermal comfort environment as it is very much energy efficient and also it could control the spreading of Biological hazards such like bacteria, virus and fungi.
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Experimental approach to investigate concrete-masonry interface
(Department of Civil Engineering, University of Moratuwa, Sri Lanka., 2011-12) Premadasa, PKS; Liyanage, SK; Ariyarathna, HDAR; Induprabha, SAD; Dilrukshi, KGS; Ratnayake, N
A masonry infill wall is a common cell in a concrete framed building. More importantly the bond between concrete and masonry has considerable effect to the performance of infill masonry walls and hence to the frame structure itself. Therefore, understanding of the element interaction between concrete and masonry become very important and has become a topic of considerable researchinterest in the past few decades. Many researchers have tried to represent this interaction numerically. However, reliable numerical analysis can be achieved only with the correct mechanical properties which are obtained experimentally. This paper presents the results of a series of experimental studies carried out to determine the tensile and shear behaviour of concrete masonry interface relevant to the Sri Lankan brick masonry. Tests were carried out in accordance with ASTM standards. In this study, the effect of the mortar designation and the joint thickness on the bond was also investigated. From the results, it can be concluded that properties of the bond is significantly affected by the roughness of the brick used and workmanship apart from the mortar designation and joint thickness. Also it can be recommended to use 10 mm mortar joints in construction, since both shear and tensile strength of the joints get reducedwhen the joints become thicker, irrespective of the mortar designation.
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The experimental investigation of failure mechanism and bearing capacity of different types of shallow foundations
(Department of Civil Engineering, University of Moratuwa, 2011-12) Fernando, N; Sendanayake, E; Sendanayake, D; De Silva, N; Ratnayake, N
The development in analysis and design of shell type foundations have led to the understanding that there are more advantages of shell type foundations compared to their conventional flat counterpart. The bearing capacities of conical and pyramidal shell foundations on dry sand were determined in the present paper by conducting laboratory model tests. The results were compare with those of circular and square flat foundations, respectively. Four foundation on dry sand were tested in which influence of the shell configuration on the bearing capacity and settlement were investigated. The present experimental study indicated admirable performance of shell type foundations with respect to ultimate and settlement characteristics. Also characteristic of deformations or the failure mechanism of both shell and its flat counterparts were simultaneously investigated by using coloured and non-coloured sand layer by layer in dry sand model.
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Failure analysis of a DBST road using mechanistic empirical method
(Department of Civil Engineering, University of Moratuwa, 2012-12) Mampearachchi, WK; Marasinghe, DL; Dahigamuwa, RMTM; Wanniarachchi, WDNG; Nawagamuwa, U; De SIlva, LIN
The objective of this research is to analyze a failure of a DBST road section using a Mechanistic - Empirical method. For this analysis, failure of A15- Trincomalee-Batticaloe road was selected.This particular road section was rehabilitated recently by extending the width of the initial road section from both the sides and soon, a large amount pot holes appeared in the newly constructed areas.Empirical methods alone failed to identify the reason behind this failure and therefore a Mechanistic - Empirical approach was used along with the KENLAYER software to analyze the section. Mechanistic approach to pavement design seeks to explain phenomena only by reference to physical causes. Thus it uses stresses, strains and deflections within a pavement structure to analyze the loads and material properties of the pavement. This study would help future engineers to identify the reason behind the failure of road sections. This will promote mechanistic softwares like KENLAYER and increase the usage of it. These softwares will make life easy for road designers and consultants and this may turn a new chapter in road designing of Sri Lanka.
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FE modeling of CFRP strengthened concrete beam exposed to cyclic temperature humidity and sustain loading
(Department of Civil Engineering, University of Moratuwa, 2011-12) Bandara, HRCS; Gamage, JCPH; Aravinda, MD; Weerakoon, SD; Ratnayake, N
Need for strengthening of civil engineering structures has been growing in recent times due to many reasons such as improper design, increased loading and environmental deterioration. Use of carbon fiber Reinforced Polymers (CFRP) has become a most promising and affordable solution for strengthening of structures due to their superior properties. The major challenge of this composite application in outdoor structures is the long term durability of the bond between CFRP sheet and the concrete substrate. Therefore, the understanding of performance of this system in different service conditions is very important.
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Framework for the estimation of overall probability of dam failure of ancient earth dams in Sri Lanka.
(Department of Civil Engineering, University of Moratuwa, 2011-12) De Silva, LIN; Premkumar, S; Ratnayake, N
Sri Lanka has a rich history of earth dam construction with over 300 large scale ancient earth dams in service, However, large number of ancient earth dams are suffering partial falier due to excessive seepage, piping and slope instability. The failure of an earth dam involves a probability of falier and therefore the individual probabilties estimated for different falier modes under various loading condition need to be combined The probability of failure tor each mode ,involves engineering assessment of the particular failure mechantsms. and looking for solutions that can reduce the probability of those falier modes or minimise the consequences of a failure. No standard framework is adopted in Sri Lanka for the estimation of overall probability of dam failure The objective of this paper is to develop a standard framework for the estimation of over orall probability of dam failure to be included in the quantitative risk assessment process for ancient earth dams in Sri Lanka. Critical loading conditions which are relevant to Sri Lanka are considered in the present study.
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FRP strengthening of concrete structures – design and practical emphasis in Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2011-12) Fernando, S; Hettiarachchi, D; Ratnayake, N
FRP Strengthening has been developed worldwide as a mean of strengthening and retrofitting concrete structures throughout past few decades. The ever increasing loads on structures and change of use demands higher load carrying capacities. The use of FRP strengthening methods has enabled the use of existing structures thus saving millions, valuable material and valuable time will otherwise be spending on demolition and reconstruction. Flowever lack of design guidance has been a critical issue in this area. The authors have carried-out a design and implementation of FRP strengthening of an existing two storey building to accommodate two more floors and a light weight roof. This paper discusses the design method, testing carried out and practical implications in FRP strengthening of concrete columns.
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Identification of WebGIS development potential and issues - a land and water case study application for Moratuwa, SrI Lanka.
(Department of Civil Engineering, University of Moratuwa, 2012-12) Chandramali, EAG; Wijesekera, NTS; Nawagamuwa, U; de Silva, LIN
Polularity of internet usuing is rapidly incerasing. Hence the demand is high for Web based GIS tools. The need to handle heavy maps and attribute datasets, often increase issues specially with aspect to the time taken to serve maps and to filter user desired information for e very. A WebGIS based land and water information management system was developed for a land extent of approximately 2.5km’- within the Moratuwa DSD of Sri Lanka. Information of roads, buildings were collected as land data while water and stream information were collected using an extensive field survey. The developed WebGIS application integrates digital base maps and feature attribute data of the selected case study area and facilitates operations through a user-interface while offering a variety of querying and reporting options. This application which was named Geoinfo WebGIS, possesses a very high potential to serve the users through i)Map to Map ii) Map to database iii) Database to Map and iv) Database to Database functions. The application was tested and verified through a consideration of user satisfaction and accuracy. Geolnfo WebGIS was developed on MS4W framework, PostgreSQL was used as the database. Non-responsive situations, high time consumption when loading the data layers, map overlaying issues and delay in refreshing the performance issues identified through the application development.