Browsing by Author "Jayasinghe, JPLM"

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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
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-Abstract
Strength assessment of steel towers
(2016-08-11) Baskaran, K; Jeneevan, G; Jayasinghe, JPLM; Hettiarachchi, HHANC
In the recent 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.