Reliability-based life-cycle cost seismic design optimization of coastal bridge piers with nonuniform corrosion using different materials

Reinforcement corrosion is the main cause of performance deterioration of reinforced concrete(RC) structures.Limited research has been performed to investigate the life-cycle cost(LCC) of coastal bridge piers with nonuniform corrosion using different materials. In this study, a reliability-based design optimization(RBDO) procedure is improved for the design of coastal bridge piers using six groups of commonly used materials, i.e., normal performance concrete(NPC) with black steel(BS) rebar, high strength steel(HSS) rebar, epoxy coated(EC) rebar, and stainless steel(SS) rebar(named NPC-BS,NPC-HSS, NPC-EC, and NPC-SS, respectively), NPC with BS with silane soakage on the pier surface(named NPC-Silane),and high-performance concrete(HPC) with BS rebar(named HPC-BS). First, the RBDO procedure is improved for the design optimization of coastal bridge piers, and a bridge is selected to illustrate the procedure. Then, reliability analysis of the pier designed with each group of materials is carried out to obtain the time-dependent reliability in terms of the ultimate and serviceability performances. Next, the repair time of the pier is predicted based on the time-dependent reliability indices.Finally, the time-dependent LCCs for the pier are obtained for the selection of the optimal design.