1. Significance of ground motion incidence angle in seismic design of bridges
- Author
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Bortoli, Marta De, Zareian, Farzin, and Shantz, Tom
- Abstract
This paper is aimed at quantifying the difference between estimates of seismic response of bridges obtained from nonlinear response history analysis and practice-oriented methods (e.g., elastic modal analysis). In particular, this study investigates the effect of the ground motion incidence angle on the structural response of bridges. A 2D SDOF system was preliminarily used to obtain a simplified model of a bridge column. The structure was modeled with two orthogonal elastic perfectly plastic springs, tuned to obtain a target fundamental period in each direction. Nine combinations of fundamental periods were considered, and three sets of 40 bi-directional ground motions each were applied to the structure. Elastic and inelastic analyses were performed using three levels of inelastic behavior, and statistical analyses were conducted to understand the influence of the incidence angle on the ductility demand. The results show a clear dependence of the ductility demand on the incidence angle, with different behaviors between structures with equal fundamental periods in the principal directions and structures with different periods. The 2D SDOF results were later compared with the response of a real bridge column, and ultimately with a bridge model. Corrective adjustment factors were obtained to transform the results of the current approach to their correct value, analyzing also their dependence on the hazard level of reference, on the structural properties, and on the bridge type. more...
- Published
- 2014
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