Browsing by Author "Baskaran, K"

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item: Conference-Abstract
Analysis of space trusses
Ganadhiepan, G; Jayasinghe, JPLM; Baskaran, K
Steel towers play a vital role in the telecommunication and power transmission sectors. These towers are usually classified as space trusses, which are amongst the most difficult structures to analyse. Many steel tower failures have happened around the world in the past. Failures of these towers not only result in direct losses but also affect the well-being of people, economy, productivity and growth of a country. According to the recent studies on full scale transmission tower tests at the Structural Engineering Research Centre in Chennai, it has been observed that several towers fail prematurely under normal loading conditions during full scale tests, indicating the need of strength esessment.Computer based finite element analysis is the most widely used method. Although computer based analysis can be accurate and time saving, such analysis outputs willnot be of much value if the engineer cannot ascertain the validity of the outputs. The general methods of manual analysis are not appropriate for the analysis of complicated space trusses such as transmission or telecommunication towers. Therefore, there is a need for a method to manually analyse complicated space trusses. This paper presents a method combining tension coefficient method and Castigliano’s theorem for the analysis of space trusses. A physical tower model tested at the Structural laboratory of University of Moratuwa and analysed using finite element method The outputs of the physical model test and the software analysis were compared with the results of the identified method It was found that the manual method results was were in good agreement with those of the physical model test and the software analysis. This paper shows the potential of this method as a simple tool to check the outputs of computer software model analyses.
item: Conference-Full-text
Comparative study of design inputs of overhead transmission line towers
(IEEE, 2021-07) Aluthwaththa, AGHAD; Baskaran, K; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Towers have been considered as the main supporting structures of transmission lines. Cost of the towers ranges from 28 to 40 percent of the total line cost. The transmission line network needs to be upgraded continuously with the increasing power demand. In fact, the towers used in Sri Lanka are the heaviest in the region and the design has been based on the CEB specifications, which has been in use for a few decades and is based on the probabilistic method with safety factors. CEB spends reasonable amount on transmission line construction. However, this cost could be reduced by optimizing the towers. To optimize the towers, need optimized design inputs with an optimum tower configuration. This study intends to identify the economic viability of the CEB design inputs against IS802:1:1 and IEC60826 inputs. The objective of the research was achieved by identifying different design inputs and analyzing two towers (one TDL, one TD3) in PLS tower software. The design was completed with ASCE10-97. Member capacity usage and the support reactions were compared while the results showed that tower weight and foundation size could be reduced by a significant margin through using either IS or IEC codes instead of CEB specifications.
item: Thesis-Abstract
Comparative study on code based analysis of steel moment resisting connections
(2015-02-22) Kodikara, KANT; Baskaran, K
Moment resisting connections are usually designed as simple or continuous although the actual behavior is known to fall between these two extreme cases. The use of semi- continuous connection results substantial savings in steel weight of the overall construction. Extended endplate and Flush end plate connections are the widely used type of connections in steel frame construction. To understand the real behavior of semi- continuous connection, full scale laboratory test is the most accurate approach, but it is time consuming and costly to undertake. Therefore other methods were developed to predict the capacity of connections. Thus, in this study three EEP and three FEP connections were analyzed using two standards (BS 5950 Part 1: 2000 and EC 3– with UK national application document). A method proposed by Steel Construction Institute (SCI) was taken into account for analyzing. The results obtained from the numerical analysis were then compared with the existing experimental test results on the resistance of moment and mode of failure to determine the accuracy of numerical analysis. Comparison between the results from numerical analysis and experiment results satisfactorily agreed.
item: Conference-Full-text
Comparative study on protective measures against spalling slab concrete
(IEEE, 2021-07) Senevirathne, L; Baskaran, K; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Concrete spelling is a major problem in reinforced concrete structures, especially in the public buildings, which were constructed some time ago. In Sri Lanka, many public buildings like schools and hospitals have this problem. Generally, authorities prohibit the use of the building area, where there is potential for concrete spalling instead of immediately repairing, because the repairing work is expensive and time consuming. This research is to study economical protective measures to prevent falling of spalled cover concrete chunks until the proper repair is done. This paper reports the results of an experimental program involving eight small scale concrete slab panels, which were installed with four different materials. Eight concrete slab panels were casted first and after 28 days the materials were installed with two distinct installation methods. The panels were subjected to area loads and failure loads were recorded. This paper includes the findings according to the observations made during the panel testing.
item: Conference-Full-text
Comparative Study On Strengthening Methods Of Steel Towers
(2014-06-09) Ganadhiepan, G; Baskaran, K
Steel towers are widely used in the telecommunication and power transmission sectors. Failure of these towers causes direct and indirect losses and disruption to the services provided by those towers. As a result, industries and general public face difficulties and the productivity of the country also gets affected. Considerable number of tower failures has taken place in both power transmission and telecommunication sectors of Sri Lanka in the recent past but only a little amount of studies has been done so far. Testing at least a tower in a transmission line is mandatory in the power transmission sector of Sri Lanka. Generally these tests are carried out at the Structural Engineering Research Centre in Chennai. It has been observed that several towers fail prematurely under normal loading conditions during full scale tests, indicating lack of strength of towers. The objectives of this study are analysing tested towers using finite element method and comparatively studying different techniques of strengthening of towers. A general purpose finite element analysis program SAP2000 was used for the modelling and analysis of towers. Finite element model of a tower which has been tested to full scale was developed and validated in SAP2000. Then different methods of strengthening were carried out to the validated model to comparatively study the effect of each method on the strength of the tower. The findings are presented in this paper
item: Conference-Full-text
Comparative study on strengthening methods of steel towers
(Department of Civil Engineering, University of Moratuwa, 2014-03) Ganadhiepan, G; Baskaran, K; Hettiarachchi, MTP
Steel towers are widely used in the telecommunication and power transmission sectors. Failure of these towers causes direct and indirect losses and disruption to the services provided by those towers. As a result, industries and general public face difficulties and the productivity of the country also gets affected. Considerable number of tower failures has taken place in both power transmission and telecommunication sectors of Sri Lanka in the recent past but only a little amount of studies has been done so far. Testing at least a tower in a transmission line is mandatory in the power transmission sector of Sri Lanka. Generally these tests are carried out at the Structural Engineering Research Centre in Chennai. It has been observed that several towers fail prematurely under normal loading conditions during full scale tests, indicating lack of strength of towers. The objectives of this study are analysing tested towers using finite element method and comparatively studying different techniques of strengthening of towers. A general purpose finite element analysis program SAP2000 was used for the modelling and analysis of towers. Finite element model of a tower which has been tested to full scale was developed and validated in SAP2000. Then different methods of strengthening were carried out to the validated model to comparatively study the effect of each method on the strength of the tower. The findings are presented in this paper.
item: Thesis-Abstract
Computerized optimization of the base width of transmission towers in Sri Lanka
(2015-02-22) Ganeshwaran, R; Hettiarachchi, MTP; Baskaran, K
Transmission line towers were mainly used in electrification works in all over the world. Optimization of base width of the transmission towers becomes necessary in order to reduce the cost and to avoid public objection. The use of narrow width tower becomes essential, as the land value appreciates drastically in Sri Lanka. This research is to design the transmission towers with reduced base width to minimize the coverage land with optimum weight and adequate strength. There were number of models selected with 14.2m base width and analyzed by reducing the width in steps from 1m to 3.2m. For this purpose computerized model analysis software named PLS Tower was used. Accordingly cost analysis was carried out for different steel prices and the cost of land. As per this study Optimum base width of 6.2m was found considering both the land & steel price. When compared with the towers used in Sri Lanka, it was found that the narrow width towers designed from this study showed a considerable amount of saving in cost and favourable impact on environmental issues.
item: Article-Abstract
Confinement effectiveness in concrete structures
(2016-08-15) Baskaran, K; Kesawan, S; Kulathunga, DDCD; Samarakoon, HMDH
From the beginning of the 19th century, confined concrete is a popular topic among researchers. This is because, the ductile behaviour and strength of the concrete increases, when it is confined. Hence confinement effect is considered in seismic design of concrete structures. To find the strength enhancement due to confinement, various models have been proposed. Some of these models are Mander's model, Shah's model and modified L-L model. These models were developed for concrete confined by spiral reinforcement, (the spiral reinforcement was anchored to the main reinforcement bars). Almost all the experiments in the past on concrete confined with spiral reinforcement were carried out anchoring the spiral reinforcement to the main reinforcement bars. In the present study experiments were carried out without fixing the spiral to the main reinforcement bars. The obtained experimental results were compared with the available models. It was found that modified L-L model was very close to the results obtained. Some applications that could use the confinement effect, such as increasing the column load carrying capacity in post construction stage and using spiral reinforcement to increase shear resistance in beams and flat slabs (punching shear) were discussed. Then the experimental results by using spiral as shear resistors were given and it was compared with the confinement effectiveness of the spiral. Areas identified for the future works have also been highlighted as ecommendations for future work.
item: Thesis-Full-text
Cost comparison between conventional and flat slab structures
Hewavitharana, N; Baskaran, K
In present era,conventional Reinforced Concrete(RC) frame buildings are commonly used for the construction. The use of flat slab building provides many advantages over conventional RC frame building in terms of architectural flexibility,use of space,easier form work and shorter construction time. In the present work conventional and flat slab four story buildings are considered for cost comparison. In this research flat slab building andnormal symmetric RCframe buildings of different spans have been studied. The cost of construction for these buildings has also been compared. To find out the cost of reinforcement, formwork, concrete on structural elements slab,beam,columns are considered.For modeling and analysis of conventional and flat slabstructures,SAP 2000 software is used.The dead loads, live loads are considered as per British Standard. The investigation shows that weight of flat slab structure is less compared to conventional slab structure. The cost of flat slab structure is less by around 12%-16% as compared to conventional slab. This study concludes that flat slab structures are the best suited for high rise buildings as compared to conventional slab structures,in terms of costof material.
item: Thesis-Full-text
Design bending moment in concrete box structures : a comparative analysis between shell and soild element models
Rasikamal, AADI; Baskaran, K
Concrete box structures are mainly used in railway and highway projects as culverts or frame bridges. Structural engineers prefer to do finite element method (FEM) analysis using shell or frame element models to obtain bending moment diagram (BMD) for design. Structures are modelled center to center supports in shell element models. BMD of general shell element models are continuous throughout the center to center spans and maximum support moment occurs at center of supports. ACI design practice recommends selecting bending moment at face of the support as design value, but BS design practice is different and obtains bending moment value at center of the support for designs. Some literature suggests tedious bending moment correction according to the stiffness of the members of the joint. In general shell element modeling, inside rigidity of supports is not considered. However general shell element models can be modified at support region to represent the rigidity of the support area. Previously tested concrete box structure was modelled using general shell, modified shell and solid elements. Results of solid element model are much closer to experimental results at supports and spans than other models. This result validated that solid element of box culvert can be used as a base for comparison of general and modified shell models. In this study, BMD of general shell, modified shell and solid element models relevant to concrete box structures were compared to load combinations relevant to Sri Lankan Railways. The results show that BMD of solid and modified shell elements are much more similar than the general shell models. Support design bending moment can be obtained from modified shell models with reliability without confusion of center or face value to select for the design as for the general shell element models.
item: Thesis-Abstract
Design/strengthening of reinforced concrete pier heads
Wickramasinghe, WR; Baskaran, K
In a developing country like Sri Lanka, it is very important to develop infrastructure to facilitate investments. In this context special emphasis should be given to the road development sector. Therefore highway projects playa major role in infrastructure development. Southern Transport Development Project is a major ongoing highway project in Sri Lanka. Package 2 of that project having 22 highway bridges and five of them are multi span structures. The intermediate supports of those structures are hammerhead piers which are having pier heads in the range of 4-5m cantilever lengths. After erection of post tensioned girders the deck slab and the diaphragms were cast in stages to make the deck slab continuous over the piers. During construction cracks of significant widths were appeared at both ends of the pier heads. In investigating the causes for cracking it was found that, 75% of main reinforcement and 65% of shear links were curtailed in the pier head over the stem area by the designer according to the instructions of the Engineer of the project. Therefore this research focuses on the curtailment of main reinforcement and shear links of a hammerhead pier. Further, the other aspect of this study is to discuss different strengthening solutions which can be applicable to this type of under-reinforced hammerhead pier. In this regard, different cantilever lengths of three dimensional hammerhead pier models were analysed with shell elements in two different orientations using the structural analysis package SAP2000. The reinforcement and shear link requirement of the pier cross head over the stem-area was calculated and the percentage of curtailment possible is presented in this report. Finally, different solutions for strengthening a hammerhead pier are-also discussed.
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Do steel transmission towers in Sri Lanka have an optimum base width?
Hettiarachchi, MTP; Baskaran, K; Ganeshwaran, R
Structural engineers responsible for designing transmission towers optimize the cost of towers by minimizing the weight of a steel tower. However, with the escalating prices of land and increasing concern on environmental issues, it is necessary to minimize the extent of land area occupied by the towers as well. This paper discusses an extensive study on the design of a typical suspension tower in a 132 kV transmission line. The base widths considered were in the range of 3.0 m to 14.2 m. Different heights of towers were considered by varying body extensions from +0 m to +12 m. The study indicated that the weight of steel tower increased 10% to 16%, whereas the land area increased approximately twenty fold. Thus the impact of land value is considerable. The overall cost of tower was computed to include the cost of steel used in the tower and value of land area. Variation in steel unit costs and land prices were also considered in the study. The optimum base widths were found to be in the range of 4.5 m to 6.0 m for lower values of land and 2.7 m to 4.2 m for higher values of land Base widths of existing towers are in the range of 6.5 m to 9.6 m. This study has thus confirmed that considerable cost savings can be realized by optimizing the cost of steel towers by incorporating the value of land as well. An optimum ratio of 6.7 has been obtainedfor height to base width for the range of towers considered.
item: Thesis-Abstract
Economical falsework solutions for concrete arch bridges
(2014-05-20) Jayakody, JAVS; Baskaran, K
The arch bridge is very strong. It looks like half a circle. Arch bridges used to be made of stone. The problem was that until the last block was in place, these bridges were unstable and could fall down. Construction field in Sri Lanka has lot of arch shape structures such as Buddhist Temples, Muslim mosque etc therefore aesthetic view of arch shape bridges are better than other shapes. Traditionally, arch bridges were constructed of stone, brick or mass concrete since these materials are very strong in compression and the arch could be configured so that tensile stresses did not develop. Contractors are not motivated to construct arch bridges due to difficulties of construction. If there is a simple method to construct an arch bridge it is economical and quick because of flow of the stream or flood will not be disturbed to the construction. Heavy machineries or advanced technology does not matter and local labour force can be utilized. In the locations which are inaccessible to transport material or heavy machineries, concrete arch is a solution with a suitable falsework. Most bridges in Sri Lanka are constructed over water ways therefore during the construction period finding a supporting base to construct an arch structure is very hard. Also river beds are located far below from the deck level of bridge and erection of stable falsework support will be another difficult task. These are the problems in arch bridge construction within the available technology of construction in Sri Lanka and tend to existing arch bridges are limited to short spans. The objective of this research was to obtaining an economical solution for this problem. In point form the scope of this research includes • find the possible methods to construct concrete arch bridges. • materials have to be used for falsework for construction of concrete Arch Bridges. • Types of Trusses possible to use as falsework. At the design stage of concrete arch bridge, suitable falsework truss also should be designed to get the support to construct the bridge. Similar to benefit of scaffoldings to building construction, falsework truss also will be benefited to arch bridge construction. It will facilitate to select different models of falsework truss for construction of various types of concrete arch bridges with higher spans or different curvatures. Steel trusses design for falsework is ideal solution because mainly simplicity of its erection process. Another option is a timber falsework for the construction of concrete arch bridge. Cost of the timber falsework is obviously high where the locations of long span of arch bridges or high level difference between river and deck of bridge. Within the Types of steel trusses economical one also has to be identified because of their cost of material and cost of fabrication. The types of steel trusses commonly used are Howe truss, Modified Howe truss, Pratt Truss or Warren Truss. Structural analysis computer software SAP 2000 was used to analyse trusses to achieve the objectives of the research. Based on the analysis of this research Modified Howe truss fabricated by steel angle iron is successful as economical falsework solution to the construction of concrete arch bridges in Sri Lanka.
item: Conference-Abstract
Effect of corrosion on compressive strength of structurally insulated panels
(2016-08-11) Baskaran, K; Gopinath, K
Demand for new construction methods are triggered due to post tsunami rehabilitations, recent landslides, floods and present developments in the North-East etc. Structurally insulated panels (SIPs) are one such system, which expedite and ease the construction work. In Sri Lanka major cities are located along the coastal belt where corrosion is inevitable. Though corrosion is not an uncommon event, effect of corrosion on load carrying capacity of SIP panels is not well documented in published literature yet. Hence, present study focused on finding the effect of corrosion on load carrying capacity and to propose durability enhancement methods of SIPs. Corrosion-induced damage was simulated in the cementitious structurally insulated panels (CSIPs) by reducing the reinforcing steel volume. Experimental investigations were carried out for SIP panels where three were having GI meshes and the other three were with chicken meshes (40% reduced steel volume) as reinforcement. All panels were testedfor compressive strength after 28 days. Durability enhancement (delaying or preventing corrosion) of CSIPs was tested by casting four panels. One panel was kept as reference panel and other three were sprayed with 0.1M Nacl solution to accelerate corrosion. Among these three panels, one panel was applied with water proofing agent and other was coated with weather shield paint and another was left uncoated. These panels were tested for compression after three months of periodic wetting and drying with salt water. 27.4% reduction in load carrying capacity was observed with chicken mesh. Moreover load carrying capacity of CSIPs were enhanced by 17.5% with weather shield paint coated and by 38.8% with water proofing agent with reference to not treated-but periodically salt sprayed panel. In this paper, in addition to comparing the durability enhancement techniques, there costs were also compared before concluding the paper with recommendations.
item: Thesis-Full-text
Evaluation of seismic capacity of existing highway bridges in Sri Lanka
Aluthapala, UL; Lewangamage, CS; Baskaran, K
Sri Lanka is an island located in the Indian Ocean and it lies in the large Indo-Australian plate seemingly far away from any of the plate boundaries. Therefore, many people believe that this fortuitous scenario makes Sri Lanka safe from earthquakes. But an intra-plate earthquake can occur anywhere at any time. Some geologists pointed out that the Indo Australian plate is being separated into two and its boundary lies 500km away from the southern coast of the country. Therefore, Sri Lanka has a moderate risk to face an earthquake. There are over 4000 bridges on National Road Network with length varying from 3.0m to 500.0m. These bridges have varying widths about 3.0m to 25.0m and some of these have been constructed more than 50 to 100 years back. They were constructed using steel concrete composite or steel. These bridges have not been designed for seismic loads and they have not been detailed for seismic effects. Therefore, it is a must to evaluate the seismic capacity of those bridges and retrofit those if necessary. This study was focused to develop a priority list (Bridge Rank) for the purpose of further investigation on seismic capacity. It was also focused to carry out a case study for a selected bridge from the developed priority list to find out its seismic capacity. Bridges on the “A” class roads with the overall length of the bridge is greater than 25m were considered in this study. To develop the priority list for thesebridges, the method given in the “Seismic Retrofitting Manual for Highway Bridges” published by the Federal Highway Administration (Report No. FHWARD- 94-052) was used. The parameters required to input to the above methodology were obtained from the previous research findings and the bridge inventory that is maintained by the Planning Division of RDA, Sri Lanka. The bridges considered under this study have low risk to fail due to possible earthquake loadings with local conditions since the bridge rank is between 0 to 24 on the scale of 100. Bridge No 1/1 on PeliyagodaPuttalam road (Japanese Friendship Bridge) was selected for further investigation from the developed priority list since it gives the bridge ranking 12. A response spectrum analysis was carried out to find the actions of the bridge during an earthquake. For the analysis of the bridge, a Finite Element Model was developed using SAP 2000. Codes of practices for Australian standards were used to find out the seismic capacities of the substructure and the actions of superstructure was compared with the originally designed actions. The bridges considered under this study have low risk to fail due to possible earthquake loadings since the bridge rank is between 0 to 24 on the scale of 100. It is proposed to replace the bridge bearings of the bridge no 1/1 on PeliyagodaPuttalam road based on the results of the case study.
item: Conference-Full-text
Experimental study on steel fibre reinforced concrete for g-30 concrete
(IEEE, 2016-05) Karththekeyan, T; Baskaran, K; Jayasekara, AGBP; Bandara, HMND; Amarasinghe, YWR
Concrete plays a major role in the construction industry. However, concrete is weak in tension, in order to overcome this, normally reinforcements are used in construction. But these reinforcements won’t be able to stop initiating tensile cracks and other defects in concrete. Aim of this study is to find the optimum volumetric percentage of steel fibre required to increase the tensile strength of concrete with laboratory experiments. For that, seven groups of grade 30 concrete were produced with the addition of steel fibres at different volumetric percentages: 0% (as a control specimen), 0.77%, 0.86%, 0.93%, 1.00%, 1.07% and 1.47% by absolute weight of concrete. Steel fibres with aspect ratio, l/d = 80 with 0.75 mm diameter and hooked at both ends, were used in this study. The effects of adding Steel fibres in concrete were measured for the cube compressive strength (fcu) and splitting tensile strength (fct). Result data clearly shows higher percentage increase in 7 and 28 days compressive stren
item: Conference-Full-text
Feasibility of Using Palmyrah and Bamboo Strips as Reinforcement in Lintels
(2016-01-06) Dias, HYV; Munasinghe, MASS; Baskaran, K
Timber species such as Palmyrah, Bamboo and Babadua have been identified to have potential to replace reinforcing steel in concrete elements. This research was conducted to assess the feasibility of using Palmyrah and Bamboo strips as reinforcing material in lintels. The low ductility of such timber specimens, as observed during the experiments, governed this selection of a lightly loaded low risk structural element for the study. Tensile strength, water absorption and desorption characteristics, associated dimensional variations, anchorage bond strength and flexural strength of Palmyrah and Bamboo strips coated with different water repellents were evaluated using a series of laboratory experiments. Having identified double varnish coated water repellent technique to give the highest anchorage bond strength and lowest water absorption, four lintels were cast keeping two as unreinforced control specimens and two reinforced with Palmyrah and Bamboo strips. While both reinforced beams exhibited under-reinforced behaviour, one with Bamboo reinforcement achieved an incremental moment capacity of 250% and the beam with Palmyrah reinforcement achieved that of 168% compared to their respective unreinforced beams. Hence, it was concluded that both Palmyrah and Bamboo shows potential to be used as reinforcement for lintels.
item: Conference-Full-text
Feasibility study of carbon black contaminated silica sand in the production of black blocks
(2013-11-26) Baskaran, K; Gopinath, K
Present study attempted to verify the feasibility of producing cement blocks by partially replacing fine aggregates with carbon black contaminated silica sand (CBCSS), which is a by-product of the tyre manufacturing process. In the present study performance tests such as compressive testing and flexural testing were conducted. In addition resistance against rain drops was measured and the quality of water, in case of inundation was also checked. As experimental investigations, eight individual black blocks were cast and tested for compressive strength and nine sample panels were made and tested for flexural and compressive strengths. In addition, pressurized drizzle test was conducted for individual blocks to study the erosion resistance characteristics against rain. Moreover, particularly in lower lands, during floods there is a room for these panels containing CBCSS being immersed under water for certain days. The present study accommodated the above through water quality test and the results were verified with drinking water specifications. Compressive strength of individual black blocks was 4.74 N/mm2, which is well above to that of the minimum requirement of 1.2 N/mm2 as per the SLS 855: Part 1: 1989. These blocks, according to the Sri Lankan Standard, could be used for both load bearing walls for up to two storeys and in any non-load bearing walls. The flexural strength parallel to the bed joint was 0.113 N/mm2, which is just below the recommended characteristic flexural strength of 0.2 N/mm2 as per the BS 5628. The flexural strength perpendicular to the bed joint was 0.61 N/mm2, which is higher than the recommended characteristic flexural strength of 0.4 N/mm2 as per the BS 5628. The pressure drizzle test being done to the black blocks was shown smaller indentation after one hour to that of a normal brick at 50 kPa pressure, which revealed a fact that black blocks are rather resistive in terms of indentation to rain to that of normal bricks. Water, in which the black blocks were immersed for three days, satisfied the standard levels for drinkable water, recommended by the SLS 614-1983, which implies the fact that black blocks would not release any additional pollutants to the existing water/flood. Hence, it shall be concluded that the black blocks could be used in constructing masonry walls.
item: Thesis-Full-text
Feasibility study on polyurathene sandwich panel for domestic construction
Fernando, WB; Baskaran, K
The place to live is the third need of mankind. Everybody try to build up a suitable mean to meet their own requirements. The Sri Lankan need always changes drastically after two decades from initial construction as the social and economical changes in the society. The use of none renewable material for short period may degrade the scarce resources. And also generate ample amount of green house gasses, which lead the global warming. Therefore in time to come, we have to switch to renewable material or reusing material. There are some materials, those are produced from garbage. This creates regenerative products on earth resource extraction circle. The polyurethane sandwich panel is a reusing material which is produced from garbage. This thesis is on feasibility study on polyurethane sandwich panel for domestic constructions. The product establishment is a derivation as a regenerative product to meet the human need of this scenario. Additionally there is a shortage of skilled labour in the country. And the cost of labour for domestic construction is a considerable portion. The time consumed for domestic construction is more than months. Therefore by introduction of polyurethane sandwich panels for domestic constructions may resolve the major problems in the domestic construction field in the country. The aim of this thesis is to introduce an engineered solution from polyurethane sandwich panel to aforesaid problems. The only drawback is the less fire rating. But currently produced materials meet the legislative and regulatory stipulations. The science and technology on this field is to be improved in time to come. The sandwich panels are having very high stiffness compared to weight and a cost effective product. Polyurethane sandwich panel material may last more than two decades without much maintenance. The polyurethane sandwich panels are used for the construction of walls and ceiling on the cold room constructions as a good thermal barrier. This thesis is to see the validity on cold room construction material for the domestic constructions. The material properties changes from supplier to supplier. Therefore it is very difficult to adopt the standard practice in design. Even though “European Recommendations for Sandwich Panels Part 1; Design”;[14] has released on year 2000. The publication has been criticized by various researches such as Narayan Pokharel and Mahen Mahendran on their publication to “Thin Walled Structures” [13]. In addition the both published documents’ equation ranges on “European Recommendations for Sandwich Panels Part 1; Design” [14] and “Thin Walled Structures” [13] do not comply with the encountered polyurethane insulative sandwich panel. Therefore the serviceability limit published by “European Recommendations for Sandwich Panels Part 1; Design” [14] has been incorporated for design serviceability limit checking. This thesis is on feasibility study of sandwich material for house constructions by means of walls, slabs and roofs. The typical two-story house and the two story cluster houses are modelled to see the engineering viability under standard loadings. The outcome revealed that the construction up to two stories is safe. Therefore further studies in this stream shall be followed in future. As per the project outcome on the clause 6.6; it reveals that the domestic constructions up to two stories may be possible under some form of local capacity enhancement methods adapted to high stresses applied locations. The economical analysis is also made in Chapter five. Accordingly the cost on individual houses and cluster houses do not change and it revealed that there is more than 41% saving compared to the conventional constructions.
item: Conference-Abstract
Finite element analysis of truss type steel bridges
(2016-08-11) Baskaran, K; Karunarathna, WWN; Gamage, HDH
This work aims towards 3-D finite element analysis of truss type steel bridges using SAP2000 software. Some of the recent bridge failures which happened in Sri Lanka were analyzed using SAP2000 software. Failure loads and failure modes of the failed bridges were compared with the finite element analysis results. Scaled down models of a Pratt type truss bridge were tested in the structural laboratory, and then failure loads and failure modes of the test models were compared with the finite element analysis predictions. Models with portal and without portal were tested separately to see the effect of end portals with the introduction of the lateral load. Scaled down model of a Tied Arch bridge was also tested to observe the failure mode and the test results were also compared with the finite element analysis results. Span vs. tonnage graphs were developed for different truss type bridges, such as Pratt, Modified Warren, Tied Arch, Inverted Arch and the Parker truss, considering them being used by pedestrians and light vehicles. The weights of the existing bridges were also compared with the obtained graphs for some of the selected truss types.