Orienting Ground Motion Inputs to Achieve Maximum Seismic Displacement Demands on Electricity Transmission Towers in Near-Fault Regions

Abstract

This investigation was focused on developing an approximate approach for properly orienting ground motion inputs to achieve the maximum displacement demands on electricity transmission towers in the near-fault regions. The approximate approach is based on the fundamentals of dynamics of structures and inspired by the classic response spectrum analysis (RSA) method. To validate the approximate approach, a prototype was identified and analyzed using two computer models with and without consideration of the interaction between the transmission towers and transmission lines. The parametric response history analyses (RHAs) using a set of pulse-type near-fault ground motion records were performed on both computer models to generate the reference data for assessing the adequacy of the approximate approach. Result comparisons show that the approximate approach remains valid for both computer models and can be used for future designs. Moreover, the analysis results demonstrate that the fault-normal (FN) direction cannot be used as a surrogate for the orientation of the ground motion components causing the maximum displacement demands on electricity transmission towers in the near-fault regions. Further, the analysis results from one computer model were used to illustrate the limitations of the current analysis strategy used in designs.