Temperature Effects on the Soil–Structure Interactions of a Semi-Integral Bridge Before, During, and After a Bushfire

The increased frequency and severity of bushfires, not only in Australia but globally, has drawn attention to their potential effects on full- and semi-integral bridges. Unlike traditional bridges, integral bridges are less able to mitigate thermal movements due to absence of expansion joints and presence of the rigid connections between the bridge deck and the end abutments. These features result in more significant thermal movements of a bridge deck being transferred to the end abutments, potentially exacerbating issues when exposed to bushfires. However, the bushfire effects on the soil–structure interactions of the integral abutment are unknown since very little is published in the geotechnical domain. As bushfires intensify and the number of integral bridges increases worldwide, there is a greater need to study the problems that may arise from bushfire effects. In response, this study conducted physical modeling to simulate the soil–structure interactions under a critical bushfire scenario with the aim to investigate the stress ratcheting and settlement behavior at the abutment–backfill interface. The study used a half-scale physical model designed to maintain the same strain and stress similarity with a 1.92 m high semi-integral bridge abutment in attempting to replicate the abutment movements experienced during a bushfire event. The modeling yielded valuable insights into the immediate and residual effects on lateral pressure and settlement issues acting on the integral abutment before, during, and after a bushfire event.