A Modal Pushover Analysis Procedure to Estimate Seismic Demands for Buildings



A Modal Pushover Analysis Procedure to Estimate Seismic Demands for Buildings:

Theory and Preliminary Evaluation

Anil K. Chopra University of California

Berkeley

Rakesh K. Goel California Polytechnic State University

San Luis Obispo

A report on research conducted under Grant No. CMS-9812531 from the National Science

Foundation: U.S.-Japan Cooperative Research in Urban Earthquake Disaster Mitigation



PEER Report 2001/03 Pacific Earthquake Engineering Research Center

College of Engineering University of California Berkeley

January 2001

1 Introduction

Estimating seismic demands at low performance levels, such as life safety and collapse prevention, requires explicit consideration of inelastic behavior of the structure. While nonlinear response history analysis (RHA) is the most rigorous procedure to compute seismic demands, current structural engineering practice uses the nonlinear static procedure (NSP) or pushover analysis in FEMA-273 [Building Seismic Safety Council, 1997]. The seismic demands are computed by nonlinear static analysis of the structure subjected to monotonically increasing lateral forces with an invariant height-wise distribution until a predetermined target displacement is reached. Both the force distribution and target displacement are based on the assumption that the response is controlled by the fundamental mode and that the mode shape remains unchanged after the structure yields.


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