Handbook of Civil Engineering Calculations

(b) Force polygon

FIGURE 4

that joint, and proceed along the polygon in the same order. This procedure shows the di-
rection in which the force is acting at that joint.
For instance, by proceeding around joint 4, CNMKB is obtained. By tracing a path
along the force polygon in the order in which the letters appear, force CN is found to act
upward to the right; NM acts upward to the left; MK and KB act downward to the left.
Therefore, CN, MK, and KB are directed away from the joint (Fig. 4); this condition dis-

(o) Truss diagram

4 panels