Lecture 34 Shear Diagram Example Problem

Lecture 34
Example Problem

Shear Diagrams

Given:
the "weightless" beam and loading condition shown.
Determine:
the shear diagram.
Lecture 34

Solution:
Construct the shear diagram by finding the sum Fy at strategic points along the length of the beam from the left end to the right. First, cut a section immediately to the right of the left reaction, which will give a shear equal to th e reaction force of 2200#. The force is posative, so the plot will lie above the x axis.

Continue to move along the beam length plotting the change in load; there is no change until the 2400# load, at which the shear drops 2400# from 2200# yielding a shear of -200#.

Again, the shear remains constant until the distributed load. At that point, it drops 400# for each foot, (or 100# for each 1/4 foot of length, etc.), with a total drop of (400#)(6ft) or 2400#. The value of the shear diagram reaches a low of -2600# at t he end of the beam.

As soon as the magnitude of the reaction at the right support is included, the diagram should close so that the shear returns to zero. The right reaction equals 2600# so the diagram does indeed close to zero.

Lecture 34 Example Problem

Lecture 34
Example Problem