Response of approach to integral abutment bridge under cyclic thermal movement

Integral abutment bridges (IABs) are increasingly preferred over expansion joint bridges due to their ease of construction, and lower maintenance and repair cost. However, no consistent design guidelines exist for IABs due to the complexities associated with soil-structure interactions and nonlinear behaviour of the backfill soil used for the abutments. The temperature-induced cyclic movement of a bridge abutment causes an increase in lateral earth pressure on the abutment wall, which could lead to stress ratcheting. After a number of thermal cyclic movements, permanent soil densification and settlement at the bridge approach will result. In order to study abutment-soil interactions at a different magnitude of cyclic loading, model scale experiments have been conducted, and soil deformations were observed and measured using particle image velocimetry (PIV) technique. Test results show that the number of loading cycles has an important effect on the escalation of lateral earth pressure and soil deformation of the retained soil. Furthermore, the formation of soil settlement and heaving was notably increased with an increase in the amplitude of cyclic movement. Findings of the research presented here assist to define the important parameters to consider in the design of the IABs, besides the possible effects on bridge approach at different magnitudes of cyclic movement.