What type of bearing allows for both longitudinal movement and rotation?

The correct answer is the rocker bearing because it is specifically designed to accommodate both longitudinal movement and rotational movements of bridge spans or structural elements. Rocker bearings typically consist of a supporting surface that allows the superstructure to rotate around a point, while also permitting any horizontal movements that occur due to temperature changes or other forces acting on the bridge.

Rocker bearings are advantageous in bridge design as they can effectively manage differential movements that might occur due to temperature change, wind, or other dynamic loads, ensuring that the structural integrity of the bridge is maintained. They often allow for rotational freedom while transferring vertical loads efficiently.

Understanding the functionality of rocker bearings is essential for bridge inspection and safety assessments, as improper operation can lead to structural issues. This is particularly important as bridges experience significant stresses due to daily traffic and environmental factors, making the ability to accommodate movement crucial.

In contrast, fixed bearings are designed to prevent movement and rotation entirely, serving primarily to anchor the structure. Sliding plate bearings allow for horizontal movement but do not facilitate rotation. Disk bearings may offer some rotation but are generally less flexible compared to rocker bearings. Each type of bearing fulfills specific roles in the performance of bridge structures, but the rocker bearing stands out for its dual functionality in both rotation and longitudinal movement.