Supports and their reaction

Structures have loads (ie forces) imposed on them in many ways. The forces are transmitted through the material used for the structure. The supports supply active forces to create equilibrium by applying an opposing force. There are various types of supports and each type is capable of supplying particular reactive forces (ie reactions).

Roller supports as well as pin or hinge supports can be used to support a structure (eg a bridge or a beam).

See the following two diagrams for examples: