How to Solve a Truss Method of Joints

Examine the truss for zero force members that can be eliminated to simplify the problem. These come in two forms: If a joint has only two members connected at their ends (such as a corner) and has no external forces exerted on it, delete the joint and both members. If three members are connected by a joint that has no external forces applied to it and two of the beams are collinear, delete the third member.

Calculate the support reactions, the forces exerted by the ground where it contacts the truss to counter external forces (such as gravity) and moments.

Draw a free body diagram of each joint, depicting compression forces as arrows pointing into it, and tension forces as outward pointing arrows. Where necessary, break down diagonally pointing forces into their x- and y-components.

Write the equations of equilibrium at each joint, balancing all horizontal forces (x), followed by all vertical forces (y).

Select a joint where no more than two unknown reaction forces are present, and use it as your starting point to begin solving the equilibrium equations. Solve for the unknown forces at the joint.

Use the solutions found at the joint in your calculations for neighboring joints. Proceed through each joint in the truss until you find all forces in each member.