For a beam with a uniformly distributed weight load of 5 kN/m, the reactions at A and B are both 15 kN. To calculate this:
Draw the beam's free body diagram, including the equivalent point load for the weight.
Sum the moments at pin support A to find the vertical reaction at roller support B:
RyB = 30 kN × 3 m/6 m = 15 kN.
Sum the vertical forces to find the vertical reaction at A:
RyA = 30 kN - 15 kN = 15 kN.
The horizontal reaction at support A, RxA, is zero.