1.2. Free-Body diagram

  • Keep all distributed loadings, couple moments, and forces acting on the member in their exact location, then pass an imaginary section through the member, perpendicular to its axis at the point where the internal loading is to be determined.

  • After the section is made, draw a free-body diagram of the segment that has the least number of loads on it. At the section indicate the unknown resultants N, V, and M acting in their positive directions.

Exemple

Determine the internal shear (V) and moment (M) acting at a section passing through point C in the beam shown in Figure (a)