Browsing by Author "Hidallana-Gamage, HD"

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item: Conference-Full-text
Case studies on blast behaviour of glass façades: Sri Lanka easter bombings
(IEEE, 2022-07) Jayaweera, GCS; Hidallana-Gamage, HD; Baleshan, B; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Sri Lanka Easter attacks were done by coordinated suicide bombers on 21 st of April, 2019. This paper investigates the damages to the glass façades due to the explosions that occurred inside the five-star hotels, Shangri-La, and Kingsbury in central Colombo. It is evident from previous explosions that the blast-related injuries are mainly caused by the free-flying glass fragments. Laminated Glass (LG) will provide better resistance to explosions that occur outside the building if they are properly designed to be held on the supporting structure. Because, if the blast pressure enters the building, it will cause severe damage to the building elements while creating injuries to the occupants. However, when an explosion occurs inside the building, damage to the building elements and occupants will be severe if the blast pressure cannot escape from the confined building premises easily. Therefore, both of these aspects should be considered when designing glass façades for a credible blast load. LG has better blast resistance than monolithic glass. This paper presents a comprehensive review on the effect of the Easter bombings on glass façades and some design strategies which can be recommended for blast-resistant glazing with the evidence from available literature and design standards.
item: Conference-Abstract
Characteristic analysis of embedded wave barrier material beside railway tracks
(Department of Civil Engineering, University of Moratuwa, 2021-11) Abiram, P; Hidallana-Gamage, HD; Hettiarachchi, P
Rail transport is one of the most effective modes of transporting goods and people among various access points. It has several benefits compared to some of the other modes of transport, such as safety, cost effectiveness, time saving, and high capacity. Forces from the result of passing vehicles and irregularities at the wheel-rail interaction, penetrate through wheel into the track, and generates vibration. The scenarios of increasing traffic congestion and civil infrastructure development in Sri Lanka, have led to the concern about the improvement of railway transportation free from propagation of vibration through ground. Using embedded barrier material within a trench beside the railway track is an effective active control strategy practiced in most of the Railway transportation sectors around the world. In this research, characteristics of the material which is used as a vibration controlling layer embedded beside the railway track within the subsoil are analysed. Initially a finite element model of a railway track was developed, and then it was validated with the field vibration measurements available in the literature. Later a parametric study was carried out by varying the properties of the vibration controlling layer within the subsoil. The vibration characteristics were compared at 2 and 3 m depths, for different Elastic modulus, density, and void ratios of the material. It was evident that barrier material with lower elastic modulus provides a better vibration screening performance. If the available barrier material has a high elastic modulus, it should be constructed deep enough to provide a better vibration screening performance. For a given depth of an embedded barrier layer, there will be an optimum unit weight, which provides a high performance of screening. It was also found that, 2 m deep barrier provides better performance than the 3 m deep barrier for a given unit weight. Increasing the void ratio will increase the pores inside the material, and hence will increase the performance of the barrier. A shallow barrier provides better performance up to a certain value of void ratio, beyond which the performance is independent of the depth of the barrier. Overall, findings of this research elaborate the optimum material characteristics of a vibration controlling layer for train induced ground vibration in different depths.
item: Conference-Full-text
Development of design guidance for circular reinforced concrete columns incorporating crack width
(2021-07) Jayaweera, GCS; Hidallana-Gamage, HD; Indrajith, WPR; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Maximum crack width of reinforced concrete (RC) structures should be controlled for satisfying the serviceability and durability requirements of the structures. However, the crack width analysis of RC structures is not much easy because of the complexity of the parameters which affect the crack width. In the Sri Lankan context, there is no specific simplified guidance in terms charts and tables for crack width calculations of circular RC columns. Hence, it is important to develop such guidance. This research deals with the crack width analysis of circular RC columns in straight viaduct sections. A comprehensive study was carried out regarding the behaviour of the cracks in circular RC columns in viaduct sections as per the design standard, BS 5400. Autodesk Structural Bridge Design software was used to perform crack width calculations and MIDAS Civil software was used to do the Finite Element Analysis (FEA) and validation process. The comprehensive design charts developed in this research will be useful in calculating the crack widths in circular RC columns without following any time-consuming methods. Therefore, the findings of this research will be helpful to enhance the efficiency of the design work related to the crack width calculations of circular RC columns.
item: Conference-Abstract
Development of design guidance for circular reinforced concrete columns incorporating crack width
(Department of Civil Engineering, University of Moratuwa, 2021) Jayaweera, GCS; Hidallana-Gamage, HD; Indrajith, WPR; Hettiarachchi, P
The maximum crack width of Reinforced Concrete (RC) structures should be controlled for satisfying the serviceability and durability requirements of the civil engineering structures. Therefore, care must be taken at the initial design stages for maintaining the possible crack widths within a permissible range which has been specified under the design standards. However, the crack width analysis of RC structures is not easy because of the complexity of the parameters which affect the crack width. If crack width calculation is skipped, the width of the cracks in real concrete structures can be larger than the maximum limiting allowable value. Circular RC columns and piles are widely used structural components in modern civil engineering construction projects. As an example, circular RC piles and columns can be seen in many expressway construction projects in Sri Lanka to support viaduct structures. The main aim of this research is to develop design guidance for circular RC columns to estimate the crack width. In the Sri Lankan construction industry, there is no specific simplified guidance in terms of charts and tables for crack width estimations of circular RC columns. Hence, it is important to develop such design guidance for circular RC columns. Although there are a variety of applications of circular RC columns in the industry, this research deals with the crack width analysis of circular RC columns in straight viaduct sections. A comprehensive study was carried out regarding the behaviour of the cracks in circular RC columns in viaduct sections as per the design standard, BS 5400. Autodesk Structural Bridge Design software was used to perform crack width estimations, and MIDAS Civil software was used to do the Finite Element (FE) analysis and validation process. The crack width can be estimated to a 0.01 mm accurately by using the charts developed in this research. This design guidance is simple to understand, and use. Hence, engineers can perform their preliminary crack width estimations with less effort using correctly specified methods. Crack width estimation charts were developed for both uniaxial bending and biaxial bending cases of short circular RC columns with a diameter of 1.5 m, C 25/30 concrete, a nominal cover of 45 mm, and the main rebars all of the same diameter. According to the parametric study done for the circular RC columns subjected to uniaxial bending, the following details were found. Crack width reduces with increasing bar diameter and number of main rebars. Crack width is low in the columns with high-grade concrete. When the ratio of Mq/Mg as defined in BS 5400 is decreased, the crack width also decreases. A significant variation of the crack width can be seen in the cases where, the ratio, Axial load (ULS)/(Column diameter)2 is in the range of 0.5 to 2.5 N/mm2. The width of the crack is significantly higher in the case of having higher bending moments with low axial forces. This research can be extended to develop design guidance for estimating the crack width following latest standards such as Eurocodes and produce more charts by accounting for the requirements of the design engineers. The comprehensive design charts developed in this research will be useful in estimating the crack widths in circular RC columns without the need to follow time-consuming methods. Therefore, the findings of this research will be helpful to enhance the efficiency of the design work.
item: Conference-Abstract
Feasibility of using pre-stressed concrete over conventional reinforced concrete in water retaining structures
(Department of Civil Engineering, University of Moratuwa, 2021-11) Madhushani, WLAC; Hidallana-Gamage, HD; Jayamangala, HAC; Hettiarachchi, P
Water is considered the source of living for every creation, as it is a crucial element for healthy living. A Safe and adequate supply of potable water is one of the basic elements for the human to sustain a healthy life. Concrete is generally the most common material of construction of water tanks and when correctly designed and constructed, will provide long life and low maintenance cost. It is important to carry out both the design and construction of water retaining structures properly, otherwise, it would not give the intended service. Water tanks must be designed so that liquid is not allowed to leak or percolate through the concrete structure during the life of the structure. With the rapid speed of urbanization, demand for drinking water has increased by many folds. Also, as demand for water tanks will continue to increase in the coming years, quick construction methods and the most economical method will be helpful in the selection of tanks for real design. PC is the best solution for that. In this paper, design guidance for PC circular water tanks resting on the ground is presented. Both reinforced concrete (RC) and prestressed concrete (PC) alternatives are compared considering the total cost of the tank. The design and construction approaches for PC circular water tanks were identified following BS 8110-1: 1985 and BS 8007: 1987. The finite element software model of each tank was developed separately and each of the circular water tanks was analysed using Midas Gen software. The FEMbased design procedure developed in this research could be used to complement and supplement the existing design methodology for PC water retaining structures. The output of reinforced concrete designs and the output of post-tensioned concrete designs were converted into structural drawings and bills of quantities. Finally, both outputs were compared. Results of the material takeoffs showed that RC is economical only for 4000 m3 or less capacity. For higher capacities, a PC tank cost about12-14% less than the corresponding RC tank at prices prevailing in 2020. The paper helps in understanding the design philosophy for the safe and economic design of water tanks with better crack control.
item: Conference-Abstract
Improve the lateral stability of variable height steel truss type pedestrian bridges in Sri Lanka
(Department of Civil Engineering, University of Moratuwa, 2021-11) Liyanage, MLLN; Hidallana-Gamage, HD; Hettiarachchi, P
This paper investigates the methods of improving the lateral stability of variable height truss type steel bridges that are used for pedestrian purposes in Sri Lanka. A bridge is a structure that provides passage without blocking the way underneath over an obstacle. A truss is one of the key engineering features related with bridges in the emerging civil engineering contest. Several truss type steel bridges have been built for pedestrian use in the recent past. Modified Warren and variable height bridges can be commonly seen in the Southern Province of Sri Lanka over the major river crossings. When designing a pedestrian bridge for local conditions, it is very important to consider the loads due to pedestrians, wind, and sometimes light weight vehicles in the rural areas. So, it is preferred to investigate the applicable truss types and their shortcomings by conducting a detailed analysis. The aim of this research is to provide an overview of the Finite Element (FE) method with the focus on lateral stability of the variable height steel truss type pedestrian bridges, their analysis, and various applications. The applicability of steel hollow and composite sections to improve the lateral stability of steel truss type bridges were studied. A comprehensive literature review was carried out to identify the behaviour of different member sections under applied loads. FE analysis was performed using the SAP2000 software to investigate the behaviour of truss type steel bridges. The loads acting on the pedestrian bridges were calculated based on BS 5400: Part 2: 1978, where the design code BS5950: 2000 was used for the design of member sections. Later, MIDAS CIVIL software was used when analysing the truss bridges having concrete infilled composite sections for the top chord members by accounting for the buckling analysis. Span vs tonnage graphs were developed for the Variable Height Arch, Inverted Arch and other selected bridge types to investigate their steel usage for different spans. Almost all the bridges consume similar tonnage up to 25 m span, and their tonnages notably varied thereafter. Results from this study indicated that variable height bridges with concrete infilled sections consume less steel tonnage compared to those with hollow sections and other truss types. Furthermore, it was evident that the steel truss bridges with circular hollow sections consume slightly less steel tonnage compared to those with rectangular hollow sections for all the spans. This trend could be seen for both hollow and infilled sections. Overall, it can be concluded that the lateral stability of variable height bridges can be improved by using infilled sections, reducing their buckling effect, which is the main shortcoming of variable height steel truss type bridges.
item: Conference-Full-text
Improve the lateral stability of variable height steel truss type pedestrian bridges in Sri Lanka
(IEEE, 2021-07) Liyanage, MLLN; Hidallana-Gamage, HD; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
This paper investigates the methods of improving the lateral stability of variable height truss type steel bridges that are used for pedestrian purposes in Sri Lanka. Several truss type steel bridges have been built for pedestrian use in the recent past. Modified Warren and variable height bridges can be commonly seen in the Southern Province of Sri Lanka related with the major river crossings. When designing a pedestrian bridge for local conditions, it is very important to consider the loads due to pedestrians, wind and sometimes light weight vehicles in the rural areas. So it is preferred to investigate the applicable truss types and their shortcomings by conducting a detailed analysis. The aim of this research is to provide an overview of the Finite Element (FE) method with the focus on lateral stability of the variable height steel truss type pedestrian bridges, their analysis and various applications. Span vs. tonnage graphs were developed for variable height (Tied Arch) and Inverted Arch bridges incorporating circular hollow, rectangular hollow and concrete infilled sections for the top chord members. Results from this study indicated that both Inverted Arch and the Tied Arch bridges with concrete infilled sections consume considerably less steel tonnage.
item: Conference-Abstract
Investigate an economical truss type steel pedestrian bridge for Sri Lanka
(2019) Bogahawaththa, PBMR; Hidallana-Gamage, HD; Baskaran, K
This study aims towards the truss type steel bridges used for the pedestrian purposes in Sri Lanka. During the recent past, several truss type steel bridges have been constructed for pedestrian usage. Modified Warren and Variable Height bridges constructed for pedestrian usage can be commonly seen in Southern Province of Sri Lanka. When designing pedestrian bridges, it is important to consider the loading due to pedestrians and also the wind action which is less critical, especially in rural areas in Sri Lanka. Using the data gathered from the field survey, literature survey and the data collected from the Road Development Authority (RDA) and Provincial Road Development Authority (PRDA), preferred truss types were selected for further investigation. Numerical modelling and analysis of truss steel bridges were carried out using SAP2000 software to identify optimum sections for a given span. Using the results obtained through numerical modelling most preferable truss types were identified with the RDA and PRDA requirements as well as codes of practices for the length, width and headroom of the trusses.
item: Conference-Full-text
Investigate the applicability of different structural configurations for bridge/ via duct pier in local expressway
(IEEE, 2021-07) Mohanakkumaran, G; Hidallana-Gamage, HD; Indrajith, R; Adhikariwatte, W; Rathnayake, M; Hemachandra, K
Piles with tie beams are mostly used as a practice in the expressway bridges in Sri Lanka. Even though it seems to be cost effective, the reliability of the substructure in some soil conditions, might be quite low when compared to other structural configurations like piles with pile cap. A study on this matter will be helpful to identify a suitable structural configuration for substructure in terms of structural, geotechnical, and economical aspects. For this study, a bridge located in the Central Expressway project in Sri Lanka was considered. Pile with tie beam configuration and 4 other possible alternative configurations for the selected bridge were identified. All five structural configurations were analysed under 3 different soil profiles which are taken from some of the locations in the Central Expressway in Sri Lanka. Some empirical equations were used to assess geotechnical aspects in terms of load carrying capacity and the expected settlement. Meanwhile, Midas Civil 2020 software was used for the structural analysis, while Euro code was referred for the structural design. Based on the results presented in this paper, it is evident that, pile cap with friction piles can be used conveniently, if proper controlled driving of piles is done.
item: Conference-Abstract
Investigating the applicability of different structural configurations for bridge/viaduct pier in local expressway
(Department of Civil Engineering, University of Moratuwa, 2021-11) Ganaatheban, M; Hidallana-Gamage, HD; Indrajith, WPR; Hettiarachchi, P
In Sri Lanka, pile with tie-beam is commonly used as the substructure in most of the expressway bridges. Even though pile with tie beam may seem to be cost effective, the reliability of the substructure in some soil conditions, may be quite low. So, a study on this situation is helpful to identify a suitable structural configuration for substructure in terms of structural and economical aspects. For this study, a bridge on the Central Expressway which has pile with tie beam configuration, was considered and 4 other possible configurations which consist of piles and pile cap, were identified with the help of codes and some textbooks. Applicability of all five structural configurations were assessed under 3 different soil profiles, which could be seen at some locations of the Central Expressway, Sri Lanka. The assessment comprises of three major components. First one is geotechnical assessment and then, structural analysis and design, followed by cost analysis. All configurations were subjected to geotechnical assessment under all 3 soil profiles and configurations that showed satisfactory results, were considered in subsequent steps. With the help of Midas civil2020, variation in the internal forces at critical locations of the bridge were obtained and studied to obtain a proper understanding in the selection of suitable configurations. In order to reinforce the selection, a cost analysis was carried out after the detailed design. During this procedure, it was noticed that greater stability and serviceability contribute to the huge material usage in proposed alternatives than in existing configuration under selected soil profiles. Thus, proposed alternatives are more expensive than existing configuration. However, the main concern of this research is to ensure the structural stability in weak soil conditions, while making it economical. So, considering all aspects, it can be concluded that pile caps can be used with friction piles conveniently for weak soil conditions if proper controlled driving of piles can be ensured.
item: Conference-Full-text
Investigation of the feasibility of prestressed concrete (PC) over conventional reinforced concrete (RC) in water retaining structures
(IEEE, 2022-07) Chathuri Madhushani, WLA; Hidallana-Gamage, HD; Baskaran, K; Rathnayake, M; Adhikariwatte, V; Hemachandra, K
Concrete water tanks are used to store and supply safe drinking water and are designed as crack-free structures. The demand for water tanks will continue to increase in the coming years; quick construction methods and economical design approaches will be helpful in the selection of water tanks for relevant applications. Prestressed Concrete (PC) will be a better alternative for Reinforced Concrete (RC) water tanks which are commonly used in Sri Lanka. This paper presents design guidance for PC circular water tanks resting on the ground. The design and construction approaches for PC circular water tanks were identified following EN 1992-1-1:2004 and EN 1992-3:2006 standards. The Midas FEA Finite Element (FE) software was used to analyse the tanks. The economic feasibility of both PC and RC tanks is compared for different tank capacities. The design outputs were converted into structural drawings and bills of quantities. Results of the material take-offs showed that RC is economical only for 4500m 3 or less capacity. For higher capacities (above 4500 m3), PC tanks become cheaper by around 12-14%. The information presented in this paper will therefore be helpful to understand the design philosophy for the safe and economical design of water tanks with better crack control.
item: Conference-Full-text
Study on concrete filled steel circular and square tubes
(IEEE, 2020-07) Bogahawaththa, PBMR; Madhuranga, KP; Hidallana-Gamage, HD; Weeraddana, C; Edussooriya, CUS; Abeysooriya, RP
Concrete filled steel tube (CFST) is a composite material which is increasingly used in the civil engineering industry. So, it is required to identify the properties of concretefilled steel tubes as a composite material. This paper focuses on a study conducted on concrete-filled circular steel tubes and galvanised square sections. Concrete filled circular steel tubes were tested under axial compression with three different diameter-to-thickness (D/t) ratios and two different concrete compressive strengths since CFSTs are most effective as compression members. Galvanised steel square sections were also tested for compression capacity and failure mode. Finite element model was developed using the ABAQUS software and two experimental programmes were carried out to find material properties of concrete and steel for finite element modelling and two experimental programmes were carried out to verify the finite element modelling. Galvanised iron square sections were modelled using MIDAS gen software and verified with experimental results for the failure load and failure mode also. The axial capacity of CFST was found theoretically using two different codes and one equation found in the literature. Experimental as well as numerical results showed that the axial capacity of CFST increases as the concrete infill increases and decreases with D/t ratios.