Experimental and numerical study on cyclic behavior of a UHPC-RC composite pier

Conventional reinforced concrete piers are vulnerable to severe compressive damage under strong earthquake conditions and are difficult to quickly rehabilitate. This paper develops a new type of composite pier, consisting of ultra-high-performance concrete (UHPC) and reinforced concrete (RC). This UHPC-RC composite pier uses a UHPC cover outside of an RC core to achieve a high load-carrying capacity and mitigate compressive damage. An experiment is performed to evaluate the performance of the UHPC-RC composite pier under cyclic deformation. The crack development, ultimate failure modes, and load-carrying capacities of the pier are observed. Because of the extraordinary compressive strength of UHPC, the composite pier suffers little compressive damage under large lateral deformations. The composite pier fails as a result of fracturing of the reinforcement. A numerical model is developed to reproduce the cyclic behavior of the composite pier. On the basis of the verified numerical model, a parametric analysis is used to investigate the influence of the thickness of the UHPC cover and the axial load ratio. Finally, an approach is recommended for designing composite piers.