Support Reactions for Beams and Load:

The conditions of equilibrium for rigid bodies may be used to discover the reactions of a beam. Depending on support conditions, beams are classified like cantilever, simply supported, continuous, propped cantilever and fixed beam. If a beam is fixed at one of the end and free at the other, it is called as cantilever. As at the fixed end neither translation nor rotation is possible, there shall be three unknown reaction components H_A, V_A and M_A.

There are three equations of the equilibrium. Therefore, these unknowns may be found out. Likewise, the reactions in case of simply supported beam can also be found out. In simply supported beam or in a beam hinged at one end and on a roller at other end, the number of unknowns is limited to three. Thus, these beams are called as statically determinate beams. You may determine the reactions using the static conditions of equilibrium. But, if the number of unknowns exceeds three as in the case of continuous beams, propped cantilever and fixed beams, you may not determine the unknowns just by making use of statical equations of equilibrium. Hence, these beams are called statically indeterminate beams. Here in this unit you shall learn to discover the reactions in case of statically determinate beams only.

Generally a beam is a structural member carrying transverse loads. These loads can be concentrated, distributed uniformly or triangular in nature.