Experimental Study of Reversed Cyclic Loading Test for Pile-to-Slab Bridge Connections

Slab bridge connections have not been as extensively discussed and tested as column-to-box-girder bridge connections have been. In a typical bridge configuration, multiple piles extend into the slab along the bent centerline. An interior pile-to-slab connection performs like a T-connection. Two full-scale, 24-in.-diameter pile-to-slab connections were tested. The first was designed on the basis of California Department of Transportation (Caltrans) criteria, which are based on box girder connection details. Current Caltrans standard pile connection details do not apply to 24-in.-diameter piles. The specimen had a flat slab and showed failure in the slab instead of the pile. The first problem with current joint design methods was the lack of longitudinal reinforcement in the slab near the pile. A second problem was the absence of any vertical stirrups or J-dowels into the joint to transfer force from the longitudinal reinforcement of the pile to the top mat of the slab reinforcement. The third problem was the limited number of vertical stirrups, because the stirrups were too far from the pile. A second T-connection specimen was tested with modified details. The new design specimen showed very good performance compared with the first specimen. The new details were developed using the strut-and-tie model and examining the specimen performance.