Behavior of Integral Frame Abutment Bridges Due to Cyclic Thermal Loading: Nonlinear Finite-Element Analysis

This paper presents a finite-element (FE) study of the behavior of integral frame abutment bridges under alternate cycles of expansion and contraction of the bridge due to seasonal temperature variations. An example RC solid-slab bridge is proposed and analyzed using an elastoplastic two-dimensional FE model. The bridge abutment is supported on a strip foundation. A multistage numerical technique is used to simulate the construction of the bridge, backfilling process, and alternate cycles of expansion and contraction of the bridge. The earth pressures on the abutment and the changes in these pressures, as well as the internal forces in the abutment, due to the cyclic thermal changes are predicted for different bridge lengths. The bridge is analyzed for a number of temperature change ranges. A comparison between the results obtained and those due to the embedded abutment counterpart structure is held. The results of analyses have shown that the design earth pressures may be appreciably affected by the bridge length, design temperature change range, the number of temperature increase/decrease cycles, type of abutment (frame/embedded), and the stiffness of the backfill material. The findings of this study may be beneficial to the enhancement of the present design guidelines of integral abutment bridges (IABs).