Longitudinal-direction design of buckling restrained braces implemented to achieve resilient multi-span bridges

Abstract

Multi-span bridges having bi-directional ductile diaphragm consisting of Buckling Restrained Braces (BRBs) can provide resilient bridges with damage-free columns, at low cost, while minimizing displacements demands to levels that can be easily accommodated. Towards the goal of better understanding the behavior of this type of bridges and its advantages, a parametric analysis was performed with regular multi-span simply-supported bridges considering variations in pier stiffness, BRB target displacement, BRB yield displacement, and numbers of spans. Bridges were analyzed in the longitudinal direction. BRBs were designed using nonlinear response history analysis. The demands of the designed bridges were analyzed to understand the influence of the various parameters considered. It was observed that the proposed system is able to reduce the demands in piers such as to keep them elastic and limit the displacement demands in expansion joints (which makes it easier to prevent unseating in retrofit situations). It was also determined that, according to fatigue damage calculations, it is not necessary to replace BRBs after an earthquake.