For many common beam configurations, determining deflections by the integration method can be a complicated process. An alternate method based on the principle of superposition can often be employed to simplify the beam deflection calculations.
The principle of superposition states that the combined effect of several loads acting simultaneously on a beam can be computed from the sum of the effects of each load applied individually.
Since beam tables in handbooks and other references often include these individual load cases, beam deflections for a complicated loading configuration can be determined by combining results from several tabulated cases.