Seismic performance of two-column bridge piers with innovative precast members and pipe pin connections

Accelerated bridge construction (ABC) has received substantial attention among bridge engineers and public officials. Some research has been conducted to investigate the seismic behavior of the entire bridge and its components constructed utilizing ABC. Two types of joints incorporated in a two-column pier model to be used in ABC are developed in this study: pipe pin connections to make hinge supports at the footings and socket details to make moment connections at column-cap beam joints. The pipe pin consists of two steel pipes to transfer the shear and one threaded bar to transfer the uplift forces. Socket connection is formed by extending the column into a pre-fabricated pocket in the cap beam and grouting the space between the column segment and the pocket. The primary objectives of this research are to investigate: (1) the performance of the proposed column-footing pipe pin, and (2) the behavior of a two-column bent utilizing column-footing pipe-pins with innovative column-cap beam fixed joints (socket connections). These innovative fixed joints use precast construction techniques and high-performance concrete to be used in ABC. Comprehensive experimental studies of pipe pin and their components, including cyclic load studies of a large-scale two-column bent model, were conducted. The proposed pipe pin detail was found to be successful even under high drift ratios. Column cap beam connections also performed well when conventional reinforced concrete was used.