Statics For Dummies

Chapter 20. Analyzing Beams and Bending Members

In This Chapter

• Explaining axial, shear, and moments as internal forces

• Computing internal forces at a point

• Developing generalized internal force equations

• Drawing shear and moment diagrams

For many engineers, the ability to analyze the internal forces of bending members is probably one of the most important skills that you can develop, partly because many structures and objects in the real world aren't just axially loaded. In fact, the beams in the floor you're sitting on (assuming it's not the ground floor) or even the rafters in your roof are all examples of bending members.

In this chapter, I help define what a bending member is, and I show you what to look for when you identify it. When you know you're dealing with a bending member, you're ready to actually compute the magnitudes of internal bending forces, and I show you how. I also decipher yet another sign convention (assumption) and show you the steps to develop generalized equations for internal loads. Finally, I show you one of the most important tools for engineers: the ability to quickly draw diagrams of these internal forces.

Defining the Internal Bending Forces

In Chapter 19, I show you how to handle truss systems, which are comprised of members subjected to only axial internal forces, which cause a member to become longer in tension and shorter in compression (see Figure 20-1).

But what happens when a member isn't loaded with just an axial load? Figure 20-1 also shows a point ...