Analysis of space trusses

Abstract

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.