Question

when a concentrated moment is applied to a beam, how does it affect the shear and bending moment diagrams?

Answer 1

When a concentrated moment is applied to a beam, it affects both the shear and bending moment diagrams. Let's examine the effects separately:

Shear Diagram:

1. If the concentrated moment is applied at a particular location on the beam, it will introduce a sudden change in the shear force at that point.
2. The magnitude and direction of the change depend on the type (clockwise or counterclockwise) and magnitude of the moment applied.
3. If the applied moment is positive (counterclockwise), it will cause an increase in the shear force on one side of the beam and a decrease on the other side.
4. If the applied moment is negative (clockwise), the effect will be opposite: a decrease in the shear force on one side and an increase on the other.

Bending Moment Diagram:

1. A concentrated moment applied to a beam will introduce a discontinuity in the bending moment diagram.
2. The magnitude and sign of the moment will determine the nature of the change in the bending moment.
3. If the applied moment is positive (counterclockwise), it will cause an increase in the bending moment on one side of the beam and a decrease on the other side.
4. If the applied moment is negative (clockwise), the effect will be opposite: a decrease in the bending moment on one side and an increase on the other.

In summary, a concentrated moment applied to a beam will lead to sudden changes in the shear force and bending moment at the location of application. The magnitude and direction of these changes depend on the applied moment's sign and magnitude.