Comparative study of design inputs of overhead transmission line towers

Abstract

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.