Cyclic Response of Precast Bridge Piers with Novel Column-Base Pipe Pins and Pocket Cap Beam Connections

Abstract

Prefabrication of structural elements is the integral part of accelerated bridge construction (ABC). Providing constructible beam-column and column-foundation connections that can tolerate inelastic cyclic deformations is the primary challenge for ABC in seismic regions. This study developed pipe pins to simulate hinge supports at the column-footing connections and pocket details to make moment connections between the columns and pier caps. The pipe pins consisted of two steel pipes to transfer the shear and one threaded rod to transfer the uplift forces. The pocket connection was formed by extending the column into a prefabricated pocket in a precast cap beam and grouting the space between the column segment and the pocket. The primary objectives of this research were to investigate (1) the seismic performance of the proposed connections, (2) the cyclic behavior of a two-column bent utilizing column-footing pipe pins at the base and pocket connections at the top joints, and (3) the performance of engineered cementitious composites (ECCs) in the pocket details and plastic hinge zone of column. Comprehensive experimental studies of the connections and their components, including cyclic load studies of a large-scale two-column bent model, were conducted. Test results showed that the proposed pipe pin detail resisted the force and deformation demands under high drift ratios with minimal damage. Furthermore, the precast cap beam remained essentially elastic, and the pocket detail behaved similarly to a monolithic moment connection in hinging the column when conventional concrete was used in the embedded region. Study results also recommend that ECC not be used in the embedded portion of the column in the pocket.