Attenuation relationship for inelastic earthquake spectra in Iran

Abstract

One of the most important components of a seismic risk analysis procedure is a suitable earthquake attenuation relationship of the area under study. Attenuation relationships express the ground motion parameters and spectral ordinates as a function of the effective parameters. The purpose of this study is to present attenuation relationships describing constant-ductility inelastic spectral ordinates and structural behaviour factors in the Iranian plateau. The plateau is divided into two seismic zones, Alborz -central Iran and Zagros, each of which is subdivided according to the ground type. A total of 954 horizontal ground motions recorded in 490 earthquakes were used. These events had surface wave magnitudes ranging from 4 . 0 to 7 . 7 with hypocentre distances greater than 10 km and often less than 200 km. Inelastic spectra for ductility ranging from 2 to 8, within the range of 0 . 05-4 s, are calculated. A gene expression programming algorithm instead of the conventional constant regression model is used to obtain the attenuation relationship for the inelastic spectra. It is proved that the proposed algorithm can develop the model precisely as a continuous function. The results show a consistency with an acceptable proportionality coefficient among the observed and anticipated results.

Attenuation Relationships for the Horizontal Component of Peak Ground Acceleration (PGAH) Using Gene Expression Programing (GEP) and Group Method of Data Handling (GMDH)

“…Other researchers who have used this method to present attenuation relationships including Kermani et al [19], Jafarian et al [20], Alavi and Gandomi [21], Ghodrati et al [22,23], and Gandomi et al [24]. The relationship presented by Alavi and Gandomi [21] in 2011 is as Equation (4).…”

“…The distance has an inverse effect on the parameters of the strong ground motion, so if the distance from the site to the epicenter is longer, the PGA will be smaller. The distance in seismology is expressed with different types, which types are: the shortest horizontal distance to the vertical rupture image (r jb ), the shortest distance to the rupture surface (r rup ), the shortest distance to the seismic rupture surface (r seis ), and distance from the epicenter (r hypo ) [23].…”

Editorial

“…In the first paper, Amiri et al (2015) present a procedure to develop an attenuation relationship for the assessment of seismic risk in different seismic zones in Iran. Authors used a GEP algorithm instead of the conventional constant regression model to obtain the attenuation relationship for the inelastic spectra.…”