Method of Joints

Method of Joints
The free-body diagram of any joint is a concurrent force system in which the summation of moment will be of no help. Recall that only two equilibrium equations can be written
 

There are many kinds of structure. This section will limit to those that are pin-connected. Two types of pin-connected structures will be covered here; pin-connected trusses and pin-connected frames. In the actual structure, the joints may be welded, riveted, or bolted to a gusset plate at the joint. However as long as the center-line of the member coincide at the joint, the assumption of a pinned joint maybe used.