What name is given to beams that rest on two supports and are free to move horizontally?

Beams that rest on two supports and are free to move horizontally are referred to as simply supported beams. This type of beam can pivot at the supports and is not restrained from lateral movement, allowing for the natural deflection under load. The primary characteristics of simply supported beams include that they can freely rotate at their ends while experiencing vertical loads, making them ideal for various structural applications where simplicity and ease of analysis are crucial.

In contrast, fixed beams are constrained at their supports, which prevents any rotation, leading to different load distribution and stress characteristics than simply supported beams. Continuous beams span over multiple supports, introducing additional complexities regarding load distribution and deflected shapes. Suspended beams, typically hanging from another structure, do not fit the definition of beams resting solely on two supports. Thus, simply supported beams are the correct classification for beams that rest on two supports and can move horizontally.