Using Buckling-Restrained Braces on Long-Span Bridges. I: Full-Scale Testing and Design Implications

Abstract

Using the Vincent Thomas Bridge (VTB) as a feasibility case study, near-fault loading protocols for qualifying buckling-restrained braces (BRBs) for use on long-span bridges were developed and are presented in a companion paper. In this paper, full-scale component testing demonstrated the ability of BRBs to sustain several consecutive near-fault loading protocols, and therefore, they are recommended as qualified for potential use on the VTB and other similar long-span bridges near seismic faults. Near-fault protocol test results led to the proposal of a new procedure for measuring unbalanced BRB compression and tension forces by testing two nominally identical braces. Other novel test variables included the use of stainless steel (SS) for several BRB yielding cores and high strain rates, characteristic of near-fault loading, in two dynamic tests. Design considerations were identified for BRBs using highly ductile SS considering its significant strain-hardening properties, as well as the increased brace force response due to the high strain rate observed for both steels.