What does a fixed bearing restrict in bridge movement?

A fixed bearing is designed to prevent any relative movement in specific directions to maintain the structural integrity of the bridge. It specifically restricts horizontal movement, which includes movement parallel to the length of the bridge. This is crucial because horizontal forces, such as those created by wind or seismic activity, can affect a bridge's performance and stability. By limiting this type of movement, fixed bearings help to ensure that the bridge remains aligned and performs as intended under various load conditions.

In the context of bridge design, fixed bearings allow vertical load transfer but do not permit horizontal displacements. They are essential in maintaining the overall stability of the structure since uncontrolled horizontal movements could lead to misalignment or even structural failure. Other types of bearings may be used to provide flexible movement in other directions (like rotational or vertical), but the role of a fixed bearing centers on restricting lateral (horizontal) movement.