A study on elastic input energy spectra for actual earthquake ground motions at stiff soil sites

Abstract

In energy-based seismic design approach, effect of ground motions on structures is considered as an energy input to structures. The earthquake input energy spectra are created combining the maximum input energies of single-degree-of-freedom (SDOF) systems having a certain damping ratio for different natural vibration periods. The determination of input energy spectra is of great importance for the energy-based seismic design since the total energy input to structural systems can be practically obtained via these graphs. This study presents the investigation of elastic input energy spectra for selected actual earthquake ground motions at stiff soil sites. Accelerogram set is selected from Pacific Earthquake Engineering Research (PEER) database for the specific range of average shear wave velocities in the top thirty meters of soils. Time history analyses are conducted for linear elastic SDOF systems having viscous damping ratio of 5% and energy-time histories are computed. Then the elastic input energy spectra for selected actual earthquake ground motions are obtained. The mean of energy spectra is investigated together with the mean plus one and two standard deviations of the energy spectra. The aim of the present study is to evaluate the earthquake input energy demand spectra of SDOF systems for stiff soil site classes. The results show that the elastic design input energy spectrum can be proposed for selected ground motions at stiff soil sites. © 2019 The authors.