Effects of the use of the surface spectrum of a specific region on seismic performances of R/C structures

Abstract

The present study pertains to the estimation of the significance of the use of the local acceleration spectrum of a region rather than the design spectra based on the linear time-history analyses of real structures in the region. The study was realized in three stages: (1) development of the target spectrum of the bedrock level accounting for the possible devastative earthquake, the distance of the region to the main fault and the earthquake magnitude; (2) establishment of the surface (local) spectrum of the region based on the bedrock spectrum and soil profile; and (3) the linear time-history analyses of the existing R/C building structures from the studied region using earthquake records that were produced by spectral matching according to the site-depended local spectrum and the design spectra of the seismic code. For this objective, the city of Kirikkale, located in mid-Anatolia, was adopted as the study region owing to the high seismic risk of the region and the presence of abundant poorly designed and poorly or non-engineered structures. The analyses indicated that the use of the local spectrum instead of the code design spectra is rather crucial in R/C structures with irregular story plans. In addition, structures with high eccentricity were obtained to be rather affected from earthquake motions compared to those with regular story plan. The use of the code design spectra provides closer and more conservative base shear, base overturning moment and lateral displacement estimates in R/C structures with regular story plans.