CERIS - 2011

Permanent URI for this collectionhttp://192.248.9.226/handle/123/18176

Browse

Now showing 1 - 20 of 23

item: Conference-Full-text
Civil Engineering Research for Industry Symposium 2011 (Pre Text)
(Department of Civil Engineering, 2011-12) Ratnayake, N
item: Conference-Full-text
Ultimate strength prediction for reinforced concrete slabs externally strengthened by Fiber Reinforced Polymer (FRP)
(Department of Civil Engineering, University of Moratuwa, 2011-12) Sivarajah, A; Abeysinghe, A; Lakshitha, M; Lewangamage, S; Ratnayake, N
This paper presents the potential use of externally bonded fiber reinforced polymer (FPR) systems to upgrade reinforced concrete slabs deficient in flexural strength. A total of five slabs, each having 500 mm width, 125 mm thickness, and 1530 mm length, were cast and tested to failure under four-point bending. Two slabs were reinforced with three number of 10 mm tor steel bars at the tension side that corresponds to 0.38% steel reinforcement ratio. One slab was used as a control whilst the other slab was strengthened with fiber reinforced polymer (FRP). Other three slabs were reinforced with four numbers of 6 mm mild steel bars at the tension side that corresponds to 0.18% steel reinforcement ratio. One slab was used as a control specimen while the other two slabs were strengthened with different arrangement of fiber reinforced polymer (FRP). In the experimental stage, the influences of FRP on the slabs were analyzed by studying their behaviour at failure.
item: Conference-Full-text
State of the art of concrete paving blocks in Sri Lanka (CPBs)
(Department of Civil Engineering, University of Moratuwa, 2011) Baskaran, K; Gopinath, K; Ratnayake, N
It is in the last five years that the stakeholders of concrete paving blocks (CPBs) are awakening to engineer the CPBs in Sri Lanka. Although large scale production of CPBs has already flourished in Sri Lanka, their adherence with stringent standards (both Sri Lankan and International) remains dubious. This reluctance to meet the performance and durability criteria according to codes of practices, curtails the life span of concrete block paved roads to a greater extent. The scope of the present paper is limited to verifying whether the local concrete paving blocks are made on par with international standards. Sample blocks were obtained from local CPB manufacturers and investigated.Though these blocks met the criteria in Sri Lankan Standard for CPBs for strength classes 2, 3, 4 roads, none of them met the compressive strength criteria for strength class 1 roads. Besides, tensile strength requirement specified in the BS EN 1338: 2003 was met by none of the blocks tested. Since, Sri Lankan Standard is planned to incorporate splitting tensile strength as the dominant measure to assess paving blocks in the near future, this study also attempted to identify a mix proportion to meet the splitting tensile strength requirement specified in BS EN 1338: 2003. When CPBs were casted using CPB making machine, an intolerable strength deviation was observed. A series of tests were conducted to explore the reasons for this.The outcome of which would help the small scale manufacturers to keep strength variations within a tolerable range, when they are using CPB making machines.
item: Conference-Full-text
Strength assessment of steel towers
(Department of Civil Engineering, University of Moratuwa, 2011) Baskaran, K; Jeneevan, G; Jayasinghe, JPLM; Hettiarachchi, HHANC; Ratnayake, N
In the recent Abstract: past, considerable number of tower failures happened in telecommunication sector and power transmission sector in Sri Lanka. However, no lessons were learnt and there is still a vacuum in strength assessment of towers. The objectives of this research are conducting data survey on failed towers in Sri Lanka and identifying causes, analysing failed electric transmission towers using finite element analysis and finding the causes for the failures and developing simple methods to check tower capacity based on available simplified models. Four telecommunication towers and a transmission tower were considered to identify the failure reasons. Structural analysis of a transmission tower was done using a finite element analysis package, SAP2000. A manual method to analyse 3D trusses was developed by combining unit load method and tension coefficient method. To ensure the validity of proposed analysis methods, a simple tower model was erected, structural analysis was done using both SAP 2000 package and manual method, failure loads were predicted using SAP 2000 package, loading was conducted and results were analysed. It is concluded that preliminary structural analysis with a specialised or a common structural analysis package, has to be incorporated into prevailing steel tower design procedures. Frequently admitted reason for telecommunication tower failures is tornados. However, nowadays towers are being overloaded with antennas without proper consultation. Therefore it is essential to carry out a detailed technical failure analysis to identify the reasons of failures. All these procedures and results obtained are discussed in detail in this paper.
item: Conference-Full-text
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.
item: Conference-Full-text
Traffic induced vibration analysis of existing steel bridge in Padeniya-Anuradhapura Road
(Department of Civil Engineering, University of Moratuwa, 2011-12) Kodikara, KATL; Morawaka, UD; GunathiIake, IAPMP; Lewanagamage, CS; Ratnayake, N
The Bridge which is located in Padeniya-Abstract: Anuradhapura road is a steel truss bridge with three spans of approximately 31m long. It is currently undergoing a development process which includes constructing a new cantilever pedestrian walkway of 1.5m in length of either side of the bridge. Because of this proposed cantilever foot walk static as well as dynamic loading will be changed. In order to ensure that the structure is safe under the additional loads, structural analysis was carried out for static condition as well as for dynamic condition to check the adequacy of structural elements.Analyses of the bridge under static and dynamic loading were done by the finite element (FE) method. The bridge model is such that the structural steel is idealized by beam elements and the deck is represented by shear flexible shell elements. The support with elastomeric bearings is idealized by using an internal element with linear springs. Modelling was carried out using commercial FE software package SAP2000. Based on the results of finite element analysis this paper suggests the effectiveness of using elastomeric bearings for enhancing vibration serviceability hence expanding life span of steel truss bridges.
item: Conference-Full-text
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.
item: Conference-Full-text
Strength enhancement in concrete confined by spirals
(Department of Civil Engineering, University of Moratuwa, Sri Lanka., 2011-12) Kaneswaran, U; Reginthan, J; Perera, HMP; Baskaran, K; Ratnayake, N.
The strength and ductility of the concrete Abstract: can be enhanced by confinement.lt can be achieved in many ways. Using spirals is one of the ways to enhance the strength by confinement. The confinement effect in concrete by spirals can be applicable to enhance the load carrying capacity of columns and shear carrying capacity of beams and flat slabs. This effect prevents structures from catastrophic failures during earthquakes. In this research study, experiments were conducted to determine the anchorage depth of the spiral, the shear enhancement in beams due to confinement by spirals and increment in failure load of flat slab panels a when spiral is used as a shear resistor. The actual shear carrying capacity and theoretical shear carrying capacity of the beams were checked using average integration method and discrete method.The experimental results indicated that the shear carrying capacity of the beam was enhanced by 35.7% for 30mm pitch spiral, 26.8% for 45mm pitch spiral and 16.1% for 60mm pitch spiral. The actual shear carrying capacity based on the experimental results matched closer to the value obtained by the average integration method. The failure load of the flat slab panel was increased by 12.3% when spiral was used as shear resistor.
item: Conference-Full-text
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.
item: Conference-Full-text
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.
item: Conference-Full-text
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.
item: Conference-Full-text
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.
item: Conference-Full-text
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.
item: Conference-Full-text
Study on the possible improvements if ICTAD specification for cohesionless soil to be used as a highway construction material
(Department of Civil Engineering, University of Moratuwa, 2011-12) Suvetha, B; Tharaka, DGS; Ranasinghe, JACL; Mampearachchi, WK; Thilakarisi, S; Rathnayake, N.
Major parts of the eastern and northern province of Sri Lanka are covered cohesionless soil. Utilization of locally available soil for the construction of the subbase of the roads will optimize the cost and reduce the adverse environmental impact. Recently cracks settlements and sandy soils. It is suspected that the usage of locally available soil would have caused this failure. Objective of the study is to assess the quality of the cohesionless soil as a highway construction material . Futher the applicability and validity of the currently used specifications for use of cohesion ess so' as a highway construction material are also evaluated. To accomplish the above tasks, the experience of the construction industry in this regard was gathered through site visits, case studies, interviews with relevant personel. Based on the collected information, a comprehensive laboratory test program was formulated to investigate the interrelationships between the soil properties such as grading, maximum dry density, CBR value, plasticity’ index, and liquid limit by mixing different types of clays with pure coarse sand. Laboratory test results and data collected from road construction project were analysed. Final results were reviewed by the senior consultant at RDA and NBRO.
item: Conference-Full-text
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.
item: Conference-Full-text
A study on sustainable consumption practices in Sri Lanka hotel sector
(Department of Civil Engineering, University of Moratuwa, 2011-12) Ratnayake, N; Miththapala, S; Ratnayake, N
Tourism is becoming a very important sector in the Sri Lankan economic development, with the end of the 30 year conflect situation. it is reported that 7.9% of ther GDP of Sri Lanka is contributed by the travel and tourism At the same time the tourism industry is one of the highest consumers of energy and natural resources and could become a cause of much envir nmen a an social concern if proper conservation measures are not implemented to reduce the rain on e country s resources. In order to address the above issue, a project called "Greening Sri Lankan Hotels* by tbe Cevlon Chamber of Commerce, under the EU funded Asia program. While the "Greening Sri Lankan Hotels” project has a target of addressing the hotels in the whole country, for the current study, a few hotels where the data was available and the potential for saving could be estimated one were selected. The study showed that even in the more sustainability- conscious hotels, there is room for improving the situation by better practices as well as better choice of equipment. It was found that on average about 30?o of the water consumption and 17% of electricity consumption can be reduced in the three hotels studied. The suggested interventions to achieve such savings would have relatively short payback periods, thus making them worthwhile. They would also reduce the carbon foot print by an average of about 26?o.
item: Conference-Full-text
Long term performance of a constructed wetland planted with Typha angustifolia
(Department of Civil Engineering, University of Moratuwa, 2011-12) Jayaweera, M; Witharana, A; Ratnayake, N
Constructed wetlands are often utilized for wastewater treatment' including removal of metals. The removal mechanism is phytoremeditation, in which plants are manipulated to immobilize the pollutants. Physico-chemical properties of substrate and its potential tor removal of pollutants also effects the performance of constructed wetlands. Many engineering studies of treatment by wetlands use a black box approach.This paper discusses the Zn uptake by Tvpha angustifoha and its distribution within the shoot (leaves and stem) and root. This was investigated by introducing different operation conditions to the constructed wetland during acclimatization with nutrients, and gradual variation of Zn loading with incremental increases. The relative changes in the substrate (clay tile) were also investigated by means of XRD, FT-IR and SEM analysis. The results revealed that the clay tile is a promising adsorption material for Zn. In addition,Typha angustifolia is found to contribute to metal trapping into the senescing plants via rhizodeposition and act as a catalyst for biochemical reactions. The interesting feature noted in the wetland was that after nearly two years of operation, almost all clay tiles around the rhizosphere of Typha angustifolia were disintegrated completely, back to the original clay, suggesting that nature helps to sustain the plants by providing an environment with less toxicity. lt could be concluded that the long term adaptation of wetland plants to heavy-metal rich environments would not help the sequestration process, and they cannot be considered to be heavy metal sinks in the aquatic system once this stage is reached.
item: Conference-Full-text
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.
item: Conference-Full-text
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.
item: Conference-Full-text
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.

Browse

Recent Submissions