Ground Motion Prediction Equation for Inelastic Spectral Displacement in Iran

Abstract

This paper is devoted to investigate the inelastic displacement spectra compatible to Iran. Owing to inadequacy of code-compliant elastic design spectra to predict structural damage during sever earthquakes, different approaches are proposed to overcome this problem. Inelastic design spectrum is one of the most well-known methods introduced by researchers. In practice, attenuation relationships can be used in probabilistic seismic hazard analysis to obtain the inelastic design spectrum. In this paper a new ground motion prediction equation has been proposed for inelastic spectral displacement. In this regard, 806 horizontal ground motions are utilized with magnitudes ranging from 4 to 7 and epicentral distances less than 200 Km which are obtained from 330 earthquakes in Iran. According to the tectonic condition, Iran zonecan be divided into two parts: Zagrosand Alborz-central Iran. However, three equations have been presented for the whole country zone, Zagros and Alborz-central Iran zones, separately. The main parameters such as earthquake magnitude, site-source distance and site conditions have been related to the inelastic spectral displacement. Based on average shear wave velocity to a depth of 30m, sites have been categorized into three classes. For practical purpose, simplified equations have been proposed to predict inelastic spectral displacements for Iran.