Draw the I.L for reaction at B and for the support moment MA at A for the propped cantilever in fig. Compute the I.L ordinates at 1.5 m intervals.

 Draw the I.L for reaction at B and for the support moment MA at A for the propped cantilever in fig. Compute the I.L ordinates at 1.5 m intervals.

 

Solution:

 

Remove the restraint due to RB (remove support B) Apply a unit displacement (upward).

When RB = 1, then YXB is the displacement at section x due to unit load applied at B.

 

 

Fig. is the influence line diagram for RB.

To get the I.L for MA have to

 

(i)                      Introduce a hinge at A and

(ii)                   We have to apply a unit rotation at A. Instead we will apply a unit moment at A find the general displacement at any x from B. We will then divide the displacement by the actual rotation at A.