Question 2.8.6: Draw the shearing force and bending moment diagrams for the ...
Draw the shearing force and bending moment diagrams for the members of the rectangular rigid-jointed frame shown in Fig. 2.8-15.
In such a problem it is helpful to separate the frame into its constituent members, as shown in Fig. 2.8-15(b) and to consider the equilibrium of the parts separately, but in a systematic manner. Starting from a point of application of known forces (in this case D) it is readily possible to evaluate the forces and moments which must act at C to ensure equilibrium. Equal and opposite forces will act, therefore, on the end C of member BC and, in turn, the equilibrium of BC will require certain moments and forces at end B. These moments and forces will act in the reverse direction at end B of member AB.
Having obtained the forces required at A it is always advisable to check the equilibrium of the whole frame, to ensure that the forces required at A to ensure the equilibrium of AB do, together with the forces at D, ensure the equilibrium of the whole frame. The shear force and bending moment diagrams for the constituent parts are shown in Fig. 2.8-15(c).