Seismic performance and retrofit of steel pile to concrete cap connections

This research is concerned with the seismic performance of steel pile-to-pile cap connections representative of construction practice in the eastern U.S. Two perspectives are considered. The first is the seismic vulnerability of existing pile cap connections, where the embedment depth of the pile inside the cap beam is small. Therefore, an initial experimental study was conducted for testing two specimens that represented existing exterior connections under cyclic lateral loading. The second perspective is the seismic design requirements for strong cap beam-to-pile connections. Hence, a theory that assumes a linear distribution of stresses along the connection embedment depth was developed, and comparisons with a finite element model were performed. A second experimental program was conducted to evaluate the performance of specimens retrofitted in accordance with the theoretical model developed in this study. The results of the second experimental study validated the proposed retrofit strategy.