Long-Term Thermal Effects on a Turn-Back Wingwall in a Semi-Integral Abutment Bridge

Wingwalls are designed as retaining walls to avoid the sliding of the backfill soil behind the bridge abutments and roadways. Using turn-back wingwalls that are parallel to the bridge diaphragm can provide support for the parapets and minimize the total longitudinal pressure on the abutments. These walls are subjected to axial forces and bending moments due to the thermal movements, which could cause cracks in the wingwalls. The objective of this study was to examine the thermal movement behavior of a turn-back wingwall in a semi-integral abutment bridge. Vertically oriented vibrating wire strain gauges were embedded in the concrete of the wingwall. Initial data were collected from April 2017 to December 2017. After one year of service, a visual inspection was conducted, and cracks were noticed at the top of the wingwall. Additional data were collected to monitor the wingwall behavior, and additional gauges were mounted across the cracks on the front face of the wingwall to monitor the behavior of the walls and the observed vertical cracks. The cracks tended to close as the air temperature decreased and open as the air temperature increased. The maximum opening of the cracks was 351 µƐ when the air temperature was 43°C, and the maximum closing was about -133 µƐ when the air temperature was -15.5°C. These cracks may affect the long-term serviceability of this type of bridge.