Environment-Induced Behavior of a Turn-Back Wingwall in a Semi-Integral Abutment Bridge

Wingwalls serve as critical components adjacent to the abutment, primarily tasked with retaining the earth filling of the approach roadways. However, it is essential to note that their structural function does not incorporate supporting the bridge under vertical loads. These wingwalls can be categorized into three main types: inline, flared, and turn-back wingwalls. These walls are subjected to cracks due to axial forces and bending from thermal movements. There is limited research on the effect of these thermal movements on turn-back wingwalls. The objective of this research is to investigate the long-term performance of turn-back wingwalls within a semi-integral abutment bridge, which relies on support from drilled shafts under environmental conditions. One wingwall along with drilled shafts was instrumented with strain gauges during the construction of the bridge. Strain and temperature were collected from the installed gauges, and the results showed that the daily and seasonal temperature changes significantly influence the strain in the wingwalls and the top of the drilled shafts. The constrained temperature-induced volumetric changes caused cracks at the front face of the wingwall to pass through the wall to the rear face. In addition, the substructure of the semi-integral bridge was simulated in a 3D finite-element model, and the field data were used to calibrate and validate the FEM model. Parametric studies were conducted on the bridge wingwalls with different wingwall types and soil backfill. The results showed that lower stiffness of soil backfill induces higher stresses in the bridge wingwalls. Moreover, inline wingwalls induce the highest thermal stresses in the wingwalls, while flared wingwalls induce the lowest thermal stress compared to the other types of wingwalls.