DYNAMIC ANALYSIS OF TRANSMISSION TOWERS UNDER STRONG MOTION

Abstract

Transmission tower lines are one of most important life-line structures. It is necessary that these structures are designed for seismicity. The dynamic behavior of a single transmission tower and transmission tower system that are linked by conductors has been studied in this research work. The dynamic analysis is performed on both the single transmission tower and the tower line system. The wind force acting on the tower is considered as an equivalent static force. The seismic analysis of the tower has been performed in SAP2000 Nonlinear computer program (SAP2000, Computers and Structures). The tower elements are modeled using 3 D frame elements. The tower has been subjected to North-ridge strong ground motion (1994) and the Koyna strong ground motion (1967) to study the dynamic behavior as described in the present work. Parametric study has been carried out by studying the influence of cable on the tower when the force in the cable is applied at different angles to the cross arms. The non-linear material behavior of the leg members of the tower has been studied when it is subjected to the two strong ground motions considered. To understand the non-linear behavior of the material bi-linear model has been considered and it is analyzed in the present work.