Application of BRB to Seismic Mitigation of Steel Truss Arch Bridge Subjected to Near-Fault Ground Motions

Abstract

In this paper, the seismic response of a steel truss arch bridge subjected to near-fault ground motions is studied. Then, the idea of applying buckling restrained braces (BRBs) to a steel truss arch bridge in near-fault areas is proposed and validated. Firstly, the basic characteristics of near-fault ground motions are identified and distinguished. Furthermore, the seismic response of a long span steel truss arch bridge in the near fault area is analyzed by elastic-plastic time analysis. Finally, the braces prone to buckling failure are replaced by BRBs to reduce the seismic response of the arch rib through their energy dissipation properties. Four BRB schemes were proposed with different yield strengths, but the same initial stiffness. The basic period of the structure remains the same. The results show that near-fault ground motion will not only obviously increase the displacement and internal force response of the bridge, but also cause more braces to buckle. By replacing a portion of the normal bars with BRBs, the internal forces and displacements of the arch ribs can be reduced to some extent, which is more prominent under the action of pulsed ground motion. There is a clear correlation between the damping effect and the parameters of BRB, so an optimized solution should be obtained by comparison and calculation.