This construction video shows how to examine a plain truss by applying method of joints. The tutorial is divided in two parts.
Method of Joints
The free-body diagram concerning any joint refers to a concurrent force system where the summary of moment is not fruitful. Recall that only two equilibrium equations should have been.
So, in order to entirely resolve for the forces functioning on a joint, a joint should be chosen with merely two unknown forces included. This is continued by choosing a joint that functions with only two members. Any unknown member is accepted as either tension or compression. If the force is opposite in action to that of the direction put on, the negative value is attained. As soon as the forces in one joint are set, their actions on nearby joints are identified. The process is sustained for resolving sequential joints until all members are organized.