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Chapter 8 Internal Loadings

One of the fundamental assumptions we make in statics is that bodies are rigid, that is, they do not deform, bend, or change shape when forces and moments are applied. While we know that this assumption is not true for real materials, we are building the analytical tools necessary to analyze deformation. In this chapter you will learn to compute the internal loads, which are the forces and moments within a body which hold it together as it supports its own weight and any applied loads.

The chapter begins with a discussion of internal forces and moments and defines a new sign conventions especially for them. Discussion of how to find internal loads at a specific point within a rigid body follows. The chapter concludes with three techniques to find internal loads throughout a beam. Note that the words loads or loading as opposed to forces are used here when we are referring to both forces and bending moments.

In courses you take after statics, determining the internal loading is the first step you will take to find stresses, strains, deformations and ultimately select the appropriate shape, size, and material necessary for structural elements to safely support the applied loads. So you are advised to pay attention, and master this topic.