(Solved): a) Use Castigliano's theory to calculate the vertical displacement of the joint A. A positive value ...

a) Use Castigliano's theory to calculate the vertical displacement of the joint A. A positive value indicates displacement in the same direction as which the 20 kN load is applied at A. A 20 kN vertical load is applied at joint \( A \) and a vertical load \( F= \) 17 kN is applied at joint D .