Shake Table Studies of a Concrete Bridge Pier Utilizing Pipe-Pin Two-Way Hinges

Pipe-pin two-way hinge details were recently developed by California Department of Transportation (Caltrans) to eliminate moments while transferring shear and axial loads from integral bridge bent caps to reinforced concrete bridge columns. The hinges consist of a steel pipe that is anchored in the column with an extended segment into the cap beam. There is no specific design guideline for these hinges, and the current design method is primeval and only controls shear failure of the steel pipe. In this study, a rational method is proposed on the basis of the possible limit states to obtain the lateral capacity of these hinges. To validate the proposed method, a large-scale two-column bridge pier model utilizing pipe-pin hinges was tested on a shake table. The model was subjected to increasing levels of one of the Sylmar-Northridge 1994 earthquake records. A comprehensive analytical modeling of the pier was also performed using OpenSees; for this purpose, a macro model was developed for pipe-pin hinges in this study. The experimental results confirmed that the hinges designed on the basis of the proposed guideline remain elastic with no damage. The good correlation between the analytical and experimental data indicated that the macro model and other modeling assumptions were appropriate.