Civil Engineering Association

SEISMIC RESPONSE OF INTEGRAL BRIDGE CONNECTIONS

This report describes a research program that involved experimental testing and force transfer modeling in order to characterize the behavior of a bridge design detail that integrates a steel superstructure with a concrete substructure using a concrete bent cap. During a seismic event, it is essential that the bent cap remain elastic. Focus of the research was therefore to establish a behavior profile of the bent cap connection to define limit states. The effect of two design parameters on the bent cap torsional behavior and moment capacity was examined through a series of four component tests. The two parameters examined included: bent cap reinforcement, and girder web configuration inside the bent cap. Results from the tests indicate a recommended design of stiffened steel girders integrated with a post-tensioned bent cap. Design guidelines for an integral bridge were developed, based on the experimental finds and force transfer models. The methodology for determining the bent cap torsional strength for a given earthquake, as well as recommended limits, is indicated in a design example.