What type of beam is defined as being supported at three or more points?

A beam that is supported at three or more points is classified as a continuous beam. This design allows for greater load distribution along its length, making it more efficient for carrying loads compared to simpler beams that are only supported at two ends. Continuous beams can span longer distances and are often used in structures like bridges and multi-story buildings, as their support configuration helps to reduce bending moments and deflections.

In the case of the other types of beams mentioned, a simple beam is typically supported at only two points, which limits its ability to distribute load effectively. A working beam is not a standard term used in structural engineering to describe supported beams, and while a strut beam may refer to a beam designed to react to applied loads, it does not specifically describe a beam supported at three or more points. Thus, the classification of a continuous beam aligns accurately with the definition provided in the question.