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Significance of rotating ground motions on nonlinear behavior of symmetric and asymmetric buildings in near fault sites

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Abstract

Building codes in the U.S. require at least two horizontal ground motion components for three-dimensional (3D) response history analysis (RHA) of structures. For sites within 5 km of an active fault, these records should be rotated to fault-normal/fault-parallel (FN/FP) directions, and two RHA analyses should be performed separately (when FN and then FP are aligned with transverse direction of the structural axes). It is assumed that this approach will lead to two sets of responses that envelope the range of possible responses over all non-redundant rotation angles. This assumption is examined here using 3D computer models of a single-story structure having symmetric (that is, torsionally-stiff) and asymmetric (that is, torsionally flexible) layouts subjected to an ensemble of bi-directional near-fault strong ground motions with and without apparent velocity pulses. In this parametric study, the elastic vibration period of the structures is varied from 0.2 to 5 seconds, and yield strength reduction factors R is varied from a value that leads to linear-elastic design to 3 and 5. The influence that the rotation angle of the ground motion has on several engineering demand parameters (EDPs) is examined in linear-elastic and nonlinear-inelastic domains to form a benchmark for evaluating the use of the FN/FP directions as well as the maximum-direction (MD) ground motion, a new definition of horizontal ground motions for use in the seismic design of structures according to the 2009 NEHRP Provisions and Commentary.

Additional Publication Details

Publication type:
Book
Publication Subtype:
Conference publication
Title:
Significance of rotating ground motions on nonlinear behavior of symmetric and asymmetric buildings in near fault sites
Year Published:
2012
Language:
English
Publisher location:
Tokyo, Japan 3/6-8/2012
Contributing office(s):
Earthquake Science Center
Description:
p. 1-10
Number of Pages:
10
Conference Title:
9th International Conference on Urban Earthquake Engineering/ 4th Asia Conference on Earthquake Engineering
Conference Location:
Tokyo Institute of Technology, Tokyo, Japan
Conference Date:
2012-03-06T00:00:00
Country:
United States