Rapid Repair Of Seismically Vulnerable Bridge Columns Following Earthquake Induced Damage

The Cascadia Subduction Zone (CSZ) earthquake has a high probability of occurrence within our lifetime, threatening bridges across the Pacific Northwest. Damage is expected to be geographically spread throughout the region and will have a nearly simultaneous impact on transportation through several important corridors. While bridge repair and replacement will ultimately be needed, priority will be placed on resuming mobility such that repairs will need to be implemented quickly. In an effort to anticipate this need, a repair method is being developed for rapid repair with the goal of achieving semi-permanent installation that also considers the different bridge damage states for future earthquakes. The proposed repair involves encasing the damaged column in a steel jacket which is then anchored to the foundation through easily replaceable ductile fuse hold-downs. The design objective is to isolate all inelastic strains to the hold-downs thus creating a low-damage solution. Full-scale cyclic tests were conducted to investigate the cyclic performance on substandard column-to-foundation specimens. The proposed repair was applied to the damaged column and the specimen was then re-tested using the cyclic loading that is representative of CSZ demands. The experiments validated the design goal of achieving restored or controlled strength, while also exhibiting no additional damage and self-centering behavior. The experiments have shown the potential of this methodology to rapidly repair earthquake damaged columns with a relatively generic approach.