MecMovies 4.0 : M15.3: Principal Stresses in a Rectangular Tube Beam

scene 4 of 14

Sum moments about $A$ to compute the reaction force at $B$ :

↺+ $\underset{}{\sum М_{A} = (3 k N / m) (2 m) (1 m) - (2 k N / m) (8 m) (4 m) + (5 k N) (2 m) + (8 m) B_{y} = 0 ∴ B_{y} = 6 k N}$

Determine the reaction force at pin $A$ by summing forces in the vertical direction:

+↑ $\underset{}{\sum F_{y} = - (3 k N / m) (2 m) - (2 k N / m) (8 m) - (5 k N) + A_{y} + B_{y} = 0 ∴ A_{y} = 27 k N - B_{y} = 27 k N - 6 k N = 21 k N}$