Understanding Shear Diagrams: Calculation Rule

How is shear calculated along the beam in a shear diagram?

a) The shear is zero everywhere

b) Shear is the integral of moment

c) Shear is equal to the area under the moment diagram

d) Shear is the sum of vertical forces to one side of the section

Answer:

Option d) is correct.

When building a shear diagram, the rule for calculating shear along the beam is that shear is determined by adding up the vertical forces applied to one side of the section. This occurs when two antiparallel forces cause shear deformation, and the shear strain is proportional to the force applied perpendicular to the transverse distance and parallel to the cross-sectional area.

Shear arises when two antiparallel forces of equal magnitude are applied tangentially to the surfaces of an object, leading to shear deformation and a gradual shift of object layers. The shear strain is related to the force applied perpendicular to the transverse distance and parallel to the cross-sectional area.

It's important to note that the integral of moment cannot typically determine shear, the shear value is not zero everywhere, and shear force is not equal to the area under the moment diagram. Shear force represents the summation of the vertical forces to one side of the section under observation.