Modular expansion joints and finger type expansion joints are two commonly used bridge deck movement devices in bridge engineering. Through different structural forms, they accommodate longitudinal expansion, contraction and rotational deformation of the beam caused by temperature changes, concrete shrinkage and vehicle loads, while preventing rainwater and debris from penetrating into beam end gaps.
Modular expansion joints are assembled from hot rolled steel sections, intermediate beams, support cross beams, displacement control boxes and rubber sealing strips. Through the coordinated operation of multiple intermediate beams and support systems, longitudinal expansion displacement is evenly distributed across individual sealing units, achieving a large cumulative expansion range. The load bearing structure of this joint type adopts a rigid steel framework capable of withstanding repeated impact from heavy traffic. Rubber sealing strips are securely embedded within steel profile grooves to form a continuous watertight barrier. Seal replacement can be carried out in sections without disrupting full width traffic flow.
Finger type expansion joints consist of interleaved finger shaped steel plates arranged in opposite directions and an anchorage system. The intermeshing finger surfaces form a continuous load bearing surface, providing smooth and comfortable vehicle passage. This joint type allows the beam to expand and contract freely along the bridge axis, with finger gaps opening and closing automatically with temperature changes, accommodating normal displacement demands without reliance on rubber sealing strips. Drainage channels beneath the finger plates help prevent debris accumulation, resulting in relatively low routine maintenance frequency.
Both joint types can be customized according to bridge design displacement, traffic load grade and installation width. For modular expansion joints, the number of modules, steel profile section height and support spacing can be flexibly adjusted per design requirements. For finger type expansion joints, tooth geometry parameters, plate thickness and material can be custom designed according to engineering requirements. The product expansion range spans from tens of millimeters to several hundred millimeters, and both types are widely used in medium to large span highway bridges, railway bridges, urban viaducts and interchange projects.
