Laboratory and numerical investigation of integral abutment connections with pile couplers

By benefiting from precast structural elements, accelerated bridge construction (ABC) strategies have received growing attention, as they can alleviate the consequences of prolonged bridge closures caused by cast-in-place (CIP) construction methods. Among various precast elements, integral abutments are commonly employed to eliminate the expansion joint between a bridge's substructure and superstructure, where the ingress of aggressive ions often requires frequent maintenance and repair. Due to the heavy reinforcement required at the bridge end region, congestion issues often arise, especially when attempting to utilize ABC. To address such issues, this study focuses on the integral abutment connection details designed with a set of pile couplers that splice the integral abutment diaphragm to the pile cap. The investigations involve full-scale laboratory experiments conducted to understand the structural response of the proposed connection details under both thermal and live loads. The main response measures obtained from the conducted tests were then compared to those recorded during a full-scale test on a CIP integral abutment with the details that represented the conventional design and construction practices. Upon completing the laboratory investigations, a series of numerical simulations were performed to evaluate the most critical connection details. The simulations explored a range of steel sections and a proposed design revision, in which the pile couplers were replaced with a bar reinforcement cage. The outcome of this study helps the bridge industry effectively use pile couplers for integral abutment connections, especially for ABC applications.