Effects of near-fault ground motions and equivalent pulses on Large Crossing Transmission Tower-line System

Abstract

The focus of this paper is the seismic response of Large Crossing Transmission Tower-line System (LCTL) to near-fault ground motions, and whether simplified pulses are capable of representing the effects of the ground motion pulses present in near-fault ground motions on seismic response. The effects of forward-directivity pulses and fling-step pulses on the response of near-fault LCTL were assessed. Results showed that near-fault pulse-like ground motions impose a larger seismic response to LCTL compared to far-field ground motions. The response of LCTL to near-fault motions shows higher scatter than the response to far-field ground motions when correlated with simple intensity measures such as PGA. Moreover, the seismic responses increase with the pulse period of near-fault ground motions. The response of LCTL to the forward-directivity ground motions and fling-step ground motions were reproduced using two new equivalent pulse models. It is shown that the equivalent pulse models can capture the important response characteristics of the near-fault record. There are significant differences between the responses of LCTL subjected to forward-directivity ground motions and the responses subjected to fling-step ground motions. Finally, the tower-line coupling of LCTL subjected to near-fault pulse-like ground motion was investigated. Results show that the effect of tower-line coupling on seismic responses of LCTL to far-field ground motions is more obvious than the responses to near-fault ground motions.