Shear Force and Bending Moment
SHEAR FORCES AND BENDING MOMENTS
Shear force. The shear force S at any cross-section of a horizontal beam is the algebraic sum of the vertical projection of all forces (including reactions) to the left of the given cross-section (where, in the sum, the projection of a force is positive if its direction is upward and negative if its direction is downward).
Bending moment. The bending moment M at any cross-section of a horizontal beam is the sum of the moments about the given cross-section of all the forces (including support reactions) to the left of the cross-section (where, in the sum, a clockwise moment is positive and an anticlockwise moment is negative).
Consider a simply supported beam AB subjected to various ...