Seismic Assessment for Retrofitted Skewed Reinforced Concrete Box Girder Bridges With Buckling Restrained Braces

Abstract eng:
In this study, buckling restrained braces (BRBs) are implemented as a potential retrofit strategy to mitigate damage in skewed bridges. For this purpose, a three-span reinforced concrete (RC) box girder skewed bridge was used as a case study. A three-dimensional (3-D) model was developed in OpenSees to incorporate BRBs between bent columns. The model includes soil-structure interaction effects adjusted by recent results from skewed backfill-abutment interaction experiments. This paper assesses the impacts of five different BRB designs on the performance of skewed concrete box girder bridges with different skewed angles. Nonlinear time history analyses (THAs) were performed to assess effect of BRBs on the seismic performance of skewed bridges. The seismic behavior of skewed bridges can be significantly different from that of straight bridges due to potential torsional effects caused by the combination of longitudinal and transverse seismic responses. Therefore, optimized BRB designs were developed for a certain skew angle. The results present a considerable vulnerability of original skewed bridges to deck rotation and shear key failure. After retrofit implementation, the BRBs in column bents can redistribute and dissipate energy in transverse direction of the skewed bridges, reducing the potential failure of the abutment shear keys and concrete columns. The influence of skew angle and BRB properties were also identified.

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