Types of the beam support

There are three basic types of the beam support considered as the plane system.

1. The movable rocker bearing (Fig. 5.2 a). This support does not prevent the rotation of the bar end and its displacement along the rolling plane. The only reaction setting up at it is perpendicular to the rolling plane and passes through the roller centroid.

The layout view of the movable rocker bearing is given in Fig. 5.2b.

Fig. 5.2.

The movable support allows the beam to change without hindrance its length under changing the temperature and to eliminate due to this the possibility of temperature stress arising.

2. The fixed rocker support (Fig. 5.2 c). This support admits the beam end to rotate but eliminates its transition in any direction. Its arising reaction can be decomposed into two components – horizontal and vertical.

3. The clamped end (Fig. 5.2 d). This fixing does not allow both linear and angular displacements of the section support. In a general case the reaction appears that can be decomposed into two components (vertical and horizontal) and the moment of clamping (the reaction moment).

The beam with one clamped end is called a cantilever beam.

If the support reaction can be determined by one the equations of statics, then the beams are called statically determinate. If the number of the unknown support reactions is more than the number of the equation of statics which are possible for the given problem, the beams are called statically indeterminate. To determine the reactions for these beams one has to write additional equations – the equations of displacement.