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Published November 2012 | public
Journal Article

Mechanism of Collapse of Tall Steel Moment-Frame Buildings under Earthquake Excitation

Abstract

The mechanism of collapse of tall steel moment-frame buildings is explored through three-dimensional nonlinear analyses of two 18-story steel moment-frame buildings under earthquake excitation. Both fracture-susceptible and perfect-connection conditions are investigated. Classical energy-balance analysis shows that only long-period excitation imparts energy to tall buildings large enough to cause collapse. Under such long-period motion, the shear-beam analogy alludes to the existence of a characteristic mechanism of collapse or a few preferred mechanisms of collapse for these buildings. Numerical evidence from parametric analyses of the buildings under a suite of idealized sawtooth-like ground-motion time histories, with varying period (T), amplitude (peak ground velocity, PGV), and duration (number of cycles, N), is presented to support this hypothesis. Damage localizes to form a quasi-shear band over a few stories. When the band is destabilized, sidesway collapse is initiated, and gravity takes over. Only one to five collapse mechanisms occur out of a possible 153 mechanisms in either principal direction of the buildings considered. Where two or more preferred mechanisms do exist, they have significant story-overlap, typically separated by just 1 story. It is shown that a simple work-energy relation applied to all possible quasi-shear bands combined with plastic analysis principles can systematically identify all the preferred collapse mechanisms.

Additional Information

© 2012 American Society of Civil Engineers. This manuscript was submitted on April 13, 2011; approved on January 30, 2012; published online on February 1, 2012. Discussion period open until April 1, 2013; separate discussions must be submitted for individual papers. The authors would like to express their deep gratitude to Professor Paul Jennings of the California Institute of Technology and three anonymous reviewers for their thorough review of this work. Their insightful comments have helped refine this article appreciably. This study was funded in part by the U.S. National Earthquake Hazard Reduction Program (NEHRP; Grant No. G09AP00063). Financial support from NEHRP is gratefully acknowledged. The first author is also grateful to the National Science Foundation (NSF), the Southern California Earthquake Center (SCEC), and the U.S. Geological Survey (USGS) for their continued support of his research program. Recent grants include NSF Grant No. CMMI-0926962 and unnumbered grants from the USGS and SCEC.

Additional details

Created:
August 22, 2023
Modified:
October 20, 2023