Effects of High-Frequency Ground-Motion Spectra in the Seismic Response of Squat RC Walls

Abstract

Due to the high-frequency content of ground motions in central and eastern United States (CEUS) sites, the US Nuclear Regulatory Commission has modified their regulatory guides to consider these effects in the evaluation of nuclear power plants. Ground-motion response spectrum at CEUS has high frequency content as opposed to a typical design spectral shape. The purpose of this case study is to evaluate the seismic response of squat RC walls subjected to seismic ground motions with response spectra having acceleration amplifications in the high-frequency zone. Incremental dynamic analyses are performed on three selected RC walls subjected to acceleration time histories compatible with spectra for CEUS sites. Several performance indicators are evaluated at different damage levels such as drifts, spectral accelerations at fundamental periods, and base shears. Fragility functions are developed to have a better idea of the damage caused by the ground motions with different spectra in the walls. Maximum drifts and the highest probability of exceeding the drift limits studied in this paper were obtained with the lowest-frequency-spectrum case.