Analysis and design of telecommunication towers for earthquake loading in Sri Lanka for sustainability

Abstract

Large number of telecommunication towers has been constructed in Sri Lanka during last few decades with the rapid development of telecommunication sector in the country. These towers play a significant role especially in wireless communication and failure of such tower in a disaster like an earthquake is major concern mainly in two ways. One is the failure of communication facilities will become a major setback to carry out rescue operations during disaster while failure of tower will itself cause a considerable economic loss as well as damages to human life in most of the cases. Therefore, design of telecommunication towers considering all possible extreme conditions is of utmost importance and a good design can be considered as a step towards a greater degree of sustainability. However, almost all telecommunication towers in this country have not been checked for earthquake loading since most of people believe that earthquake threats are not that much of significance to Sri Lanka until recently. With many tremors recorded in recent past, designers have started to rethink about earthquake design of structures and main objective of this research is assessing the performance of exiting towers (which were not initially designed considering earthquake loading) under possible earthquake loading and find cost effective strategies for retrofitting in case such action has to be effected. Accordingly, behaviour of existing four legged Greenfield towers under seismic loadings appropriate for Sri Lankan conditions were analyzed using equivalent static load method given in ANSI/TIA-222-G. This can be considered as an initiative in this research area under local conditions. Results and conclusions based on this analysis are discussed in this paper.