Rule 1
Concentrated
forces cause a jump (i.e.,
a discontinuity) in the shear diagram at the location of the force. The jump is in the same direction as the concentrated force arrow.
Rule 2
The change in shear force between any two locations is equal to the area under the distributed load diagram.
Rule 3
The slope of the shear diagram at any location is equal to the distributed load value (both magnitude and sign) at that location.
Rule 4
The change in moment between any two locations is equal to the area under the shear diagram.
Rule 5
The slope of the moment diagram at any location is equal to the shear force at that location.
Rule 6
Concentrated external moments cause a jump (i.e., a discontinuity) in the internal bending moment at the point of application. A CW external moment causes the moment diagram to jump up.