Akademik Veri Yönetim Sistemi
Structures, cilt.79, 2025 (SCI-Expanded)
The maximum isolator displacement has been obtained using the Equivalent Linear Static Procedure (ELSP) in the seismic design codes. In the literature, there is no consensus on whether the code-based maximum isolator displacement provides sufficient safety. The fragility-based studies show that the exceedance probability of the code-based maximum isolator displacement exceeds acceptable limits. However, many studies focusing on the specified intensity level have demonstrated that this displacement is conservative. This study clarifies the controversial results of the different studies by using the directionality effects of ground motions. For this purpose, two base-isolated buildings are modeled, one in the near-fault site and another in the far-field site. Then, the maximum directions of 53 near-fault and 79 far-field ground motions are obtained using different intensity measures, and base-isolated models are subjected to the related ground motions. For both ground motion sets, isolator displacements significantly increased by considering the effects of directionality. The exceedance probability of maximum isolator displacement obtained using the code-based ELSP method is 24.5 % for near-fault ground motions and 15.2 % for far-field ground motions. Also, it is shown that all ground motions that cause the isolator displacements to exceed the code-based limit have higher Spectral Shape Factors (SSFs) than those of the Uniform Hazard Spectra. In addition, it is shown that the effectiveness of the ELSP method is highly correlated with the SSF of the ground motions, and it is conservative for ground motions with high SSFs and unconservative for ground motions with low SSFs. Further, the code-based ELSP method is modified to incorporate the spectral shape effects into the estimation of isolator displacement, and a proposal is given to consider the isolator bidirectional displacement.