Lesson: Tension and Compression Forces in a Beam

Version 1.00
Civil Engineering,

This lesson is designed to further student understanding of tensile and compressive forces in structural beams. Specifically, to identify beams under tensile and compressive loads and how inertia affects the amount of deflection.

Beams horizontally positioned in structures like buildings and bridges are subject to loads. The loads are usually applied to the beam as a result of the weight force acting on the beam from objects positioned on top of it. It should be understood that the weight of the beam itself constitutes a load. In this case, the load is distributed along the beam length, rather than applied at a point. It is necessary to be able to use characteristics of the beam along with the applied loads to estimate how much the beam will bend when subjected to loads. When the beam has loads applied to it, some parts of the beam will be stretched as the beam bends (that is, subjected to tensile forces) and other parts will be compressed. Identification of these forces within the beam is important because some materials are better than others at withstanding these forces. This exercise involves a number of tests on a model of a simply supported beam with an overhanging end.