Lateral Cyclic Response of Large-Scale Bridge Piers with Double Steel and Hybrid Layers of Longitudinal and Transverse Reinforcements: An Experimental Study

Abstract

To ensure acceptable ductility and post-yield stiffness for bridge piers in seismic regions, double-confined steel (DCS) reinforced concrete (RC) bridge piers could be effective design options. However, steel corrosion is a major problem for the long-term durability and resiliency of such important infrastructures. To protect such bridge columns, this study proposes that the exterior reinforcement layer be constructed with glass fiber reinforced polymer (GFRP) to protect it from deleterious substances and protect the inner steel reinforcement layer. The use of double-confined hybrid (DCH) offers improved distribution and ease of construction. The double-confined section consists of three levels of confinement: unconfined concrete (cover), singly confined concrete (between the two layers of spirals), and doubly-confined concrete (inside the inner layer of spirals or the core). However, one of the main challenges for DCH under lateral loads is finding a balance between durability and ductility requirements. This study delves into the behavior of reinforced concrete (RC) bridge piers, particularly DCS and DCH, under quasi-static cyclic loading. Through comprehensive experimental testing, the research showcased the distinct behavior of DCS and DCH in terms of their lateral load-carrying capacity, damage progression, and ductility. The observed hysteresis loops for both types denoted unique energy dissipation characteristics. Emphasis was given to the performance-based seismic design (PBD) approach, a method now prevalent in design codes. In line with CSA S6-19 guidelines, four performance levels were established, reflecting different damage states. The research further discussed the effective flexural stiffness of these configurations, noting variations based on axial load ratios. Furthermore, a practical design example based on PBD was presented, shedding light on the seismic behavior of RC bridge piers, with a focus on reinforcement configurations.