Bridge Expansion Joint for Bridges with Expansion Joints in Deck Slabs on Grade

Approach slabs and deck slabs on grade at bridge abutments require expansion joints that accommodate the movement of the slab relative to the bridge deck and the approach pavement. The joint design must prevent differential settlement and maintain a smooth riding surface. Approach slab function is to provide a smooth transition between the bridge deck and the approach pavement. The approach slab is supported on the abutment at one end and on the approach fill at the other end. The expansion joint at the bridge end of the approach slab accommodates the movement of the bridge deck relative to the approach slab. Approach slab movement is driven by the thermal movement of the bridge deck, which is transmitted to the approach slab through the connection at the abutment. The approach slab slides on the approach fill as the bridge deck moves, creating a movement joint at the end of the approach slab. Differential settlement at approach slabs is a common problem that creates a rough ride and vehicle impact loading. The approach slab must be supported on a stable foundation to minimize differential settlement. Piles or ground improvement may be required if the approach fill is compressible. Sleeper slab design at the end of the approach slab provides a stable support for the approach slab and prevents settlement. The sleeper slab is a concrete beam that is supported on piles or on a stable foundation. The approach slab rests on the sleeper slab and is connected to it by a hinge or a sliding connection. Maintenance of approach slab expansion joints requires annual inspection of the joint condition and the approach slab level. Any step at the joint must be corrected promptly to prevent vehicle impact loading. Differential settlement of the approach slab must be monitored and corrected before it causes significant problems.