Influence of equivalent pulses of near fault ground motions on base-isolated RC structures

During past decades, increasing database of recorded ground motions demonstrated that near fault ground motions are significantly different than other ground motions. These pulse-type motions have the strongest at longer periods and they can place severe demands on structures in the near-fault region. In this study, it is aimed to use equivalent pulses of near fault ground motions as actual records for investigating seismic response of base-isolated structures. A new wavelet is used for simulating equivalent pulses of actual near fault ground motions. In order to evaluate the seismic response of base-isolated structures, different detailed 3D nonlinear analytical models with different characteristics are developed and analyzed under significant pulse like near fault ground motions and their equivalent pulses. The parametric study is concentrated on base shear, accelerations and displacements of isolated models. Also the comparison between hysteretic responses of models as a main criterion for energy dissipation of system has been investigated and evaluated. The results indicated that base displacement responses of base-isolated models under equivalent pulses almost completely match with base displacement responses under the related actual records of near fault ground motions.