Seismic performance of bridges to a spatially varying horizontal and vertical earthquake ground motion

Document Type : Research Article

Authors

1 Faculty of Engineering, Kharazmi University, Tehran, Iran

2 Faculty of Engineering, Kharazmi University, Tehran, Iran.

3 Faculty of Engineering, Kharazmi university, Tehran, Iran

Abstract

Considering the spatial variations of ground motions in the design of extended structures, especially bridges, is of importance. In this paper, the effect of spatial variations of the ground motions on bridges regarding the horizontal and vertical components of the earthquake was investigated. A five spans bridge is modeled in OpenSees and 3D nonlinear dynamic time history analysis is performed. The generation of acceleration time histories is in accordance to the spectral-representation-based simulation algorithm which has been presented in previous studies.
Seismic performance of the bridge was studied by considering the identical and differential support ground motions. Shear force, bending moment, displacement of bridge piers in identical and differential excitation supports with different soil conditions were analyzed.
The results showed that by considering the spatial variations of ground motions, internal forces made significant changes at the piers of the bridge. Based on the results by assuming the spatial variation of ground motion, bridge responses in piers will grow considerably; the axial, shear force and bending moment in the bridge piers calculated 1.87، 1.8, 1.97 times, respectively, compared to the identical support ground motion. Furthermore, the influence of soil type of the construction site has been investigated. The results illustrated that the non-homogeneous sites lead to the increase in axial force about 55% in the bridge piers.

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