What Is a Bridge Bearing?

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 bridge bearing is a construction method that allows a bridge to transfer forces from its deck down into its foundation without damage. These bearings are used in bridges, but similar layers may be found roads, docks, airports and other structures where large and heavy objects need to operate safely. Basically, the surface of the structure and the foundation of the structure have a layer between them that both absorbs and transfers energy. When the surface is under pressure or struck by a large force, it will transfer the energy into the bridge-bearing layer, which then sends it to the foundation to dissipate.

The bridge bearing is generally easy to find when looking at a bridge’s structure. Most bridges will have a solid road surface and a series of supports underneath it. Between these two sections are the bearings. These bearings will have a wide range of appearances, but they are generally disproportionately small—much smaller than the road deck and usually smaller than the support it sits on.

The bearing’s small size allows forces from the road deck to converge into a very small point. When that energy travels down into the foundation, it travels as a very compact line of force. Since only a small part of the foundation is moving the energy, the rest of the system supports it as the energy moves. This reduces the shearing force on the foundation and makes it less likely to fail during the transference.