A P /V P specific inelastic displacement ratio for seismic response estimation of structures Cengizhan Durucan and Murat Dicleli* ,† Department of Engineering Sciences, METU, Turkey SUMMARY In this study, two new site specific statistical equations are proposed to estimate the inelastic displacement ratio, C 1 of structures subjected to far fault (FF) and near fault (NF) ground motions. The proposed equations consider the effects of fundamental vibration period of the structure, T, lateral strength ratio, R and frequency content of the design earthquake record represented by the A p /V p ratio (or T 0 = 2π/A p /V p ), which is a function of the earthquake magnitude, distance to fault, faulting mechanism and site class. It was observed that the C 1 values obtained from the proposed equations are in good agreement with the calculated results. The flare of the plotted C 1 vs. T/T 0 curves enables the proposed equations to cover nearly all the calculated C 1 data range and give satisfactory results. However, the curves obtained using the C 1 equations of several codes and those available in the literature do not cover the whole calculated C 1 data range and generally give unconservative results (smaller C 1 values) especially in the shorter period range. For the longer period range, the predictions of C 1 obtained from the proposed equation and the ones available in the literature are in good agreement with the calculated C 1 data. Copyright © 2014 John Wiley & Sons, Ltd. Received 7 May 2014; Revised 17 August 2014; Accepted 25 September 2014 KEY WORDS: inelastic displacement ratio; performance-based analyses; frequency content; site specific 1. INTRODUCTION In many municipal areas around the world, several destructive earthquakes in the last two decades (Kobe—1995, Kocaeli—1999, Gujarat—2001, Iran—2003, Sumatra—2004, Pakistan—2005, China— 2008, Haiti—2010, Japan—2011) resulted in extensive damage to buildings and bridges. Practically most of the structural and nonstructural damage sustained in structures was produced by lateral displacements, stressing the necessity for the accurate estimation of the seismic lateral displacement demand of structures in the design phase. There are several linear and nonlinear analysis methods to determine the seismic demands on a structure. If the structure responds beyond the elastic limits simple linear analyses procedures fail to accurately predict the failure mechanisms, forces and displacements. On the other hand, nonlinear dynamic analysis procedure is the most accurate method of computing the seismic demands in structures, but it requires a large number of well suited earthquake time-history records and corresponding nonlinear time history analyses (NTHA), which involve excessive computational effort and associated convergency problems rendering such analyses ineffective. Nonlinear static procedures (NSPs) are thus invented to offer a balance between the simplicity of linear static analysis and complexity of NTHA [1] Furthermore, NSPs may be efficiently used in performance- based design (PBD) method, which is based on matching various probable earthquakes (or in static pushover procedures, target displacements) with target performance levels (PLs). *Correspondence to: Murat Dicleli, Engineerimg Sciences, Middle East Technical University, Turkey. † E-mail: mdicleli@metu.edu.tr Copyright © 2014 John Wiley & Sons, Ltd. EARTHQUAKE ENGINEERING & STRUCTURAL DYNAMICS Earthquake Engng Struct. Dyn. 2015; 44:1075–1097 Published online 21 October 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/eqe.2500