In architectural structures, supports refer to the part of the structure which may help other parts to resist loads. Columns, walls, and foundations are the obvious support systems in an architectural structure. In addition, a beam can support another beam.
To simplify the understanding of the support actions, we generally divide them into three types:
Roller Support: This is the type of support which only restrains the structure from moving in one or two perpendicular directions. However, the structure can move in the other directions and it can also rotate. The joint that is supported by a roller support has four or five degrees of freedom.
A Roller Support
If the structure acts as a two-dimensional system, the roller support restrains the node form moving in one direction only. In general, there is a support reaction (force acting from the support to the structure) in the direction of the restrained degree of freedom. Therefore, roller supports have one or two support reactions. Roller supports are used in bridges and spatial structures to allow for thermal movements.
Pin-support: Pin or hinge support is used when we need to prevent the structure from moving or restrain its translational degrees of freedom. Most supports for architectural structures (except concrete structures) are of this type. When used for spatial structures, these supports have three reactions; however, there are only two reactions in two-dimensional structures.
A Pin-Support
Fixed-support: A fixed support prevents all movements and rotations at the point where it is attached to the structure. The joint with fixed support has no degrees of freedom, and therefore, there are six support reactions applied from the support to the structure.
