Shear Diagram

The shear diagram is a graphical representation of the distribution of the shear forces along the beam's length.

Consider a beam AB supported at two ends and subjected to perpendicular loads. Construct its shear diagram.

Draw the free-body diagram of the beam. Using the equilibrium equations of force and moment, the reaction forces at each support can be calculated.

Apply the method of section to the beam.

Next, consider an arbitrary distance from point A within the region AP. Draw a free-body diagram of the section. Under the equilibrium condition, the shear force in the section equals the reaction force at the support.

Similarly, consider an arbitrary point within the region PQ. By drawing the free-body diagram and using the equilibrium equation, the shear in the section can be determined.

Finally, the arbitrary point is considered within section QB. By drawing the free-body diagram and recalling the equilibrium equation, the shear in the section can be determined, which remains constant until the beam's end and ultimately goes to zero to maintain equilibrium.