Bridge Expansion Joint for Bridges with Integral Wing Walls

Bridges with integral wing walls have the wing walls connected to the abutment and the deck, creating a rigid connection that restrains the thermal movement of the deck. The expansion joint must be designed for the reduced movement that results from this restraint. Integral wing walls provide lateral restraint to the bridge deck, preventing the deck from moving laterally under thermal loading. This lateral restraint reduces the lateral component of the thermal movement at the expansion joint. However, the longitudinal component of the thermal movement is not affected by the wing walls. Structural analysis of bridges with integral wing walls must consider the restraint provided by the wing walls. The wing walls create horizontal forces in the deck and the abutment that must be resisted by the structural system. The expansion joint must be designed for the movement that results from this analysis, not the free thermal movement of an unrestrained deck. Wing wall design must accommodate the forces from the deck thermal movement. The wing walls must be designed to resist the horizontal forces from the deck without cracking or yielding. The reinforcement in the wing walls must be adequate for the combined effect of earth pressure, thermal forces, and any other loads. Approach slab design for bridges with integral wing walls must accommodate the movement of the deck relative to the approach fill. The approach slab is connected to the deck at one end and rests on the approach fill at the other end. As the deck moves, the approach slab slides on the approach fill, creating a movement joint at the end of the approach slab. Monitoring of bridges with integral wing walls is recommended to verify that the movement distribution matches the design prediction. Displacement sensors at the expansion joint and strain gauges on the wing walls can measure the actual movement distribution. Any significant deviation from the design prediction should be investigated.