Problem $5(20$ points; $5$ points each part$).$

A$)$ Draw the influence line for the structure below, for shear at $L.$

B$)$ Derive the stiffness coefficient $k_{22}$ for the beam element.

C$)$ Formally define the meaning of flexibility coefficient. Draw a diagram illustrating what the flexibility coefficient $f_{22}$ is for a beam element.

D$)$ Sketch the moment diagram for the following structure. Indicate values and all important points on the diagram.