How Do You Interpret Shear and Moment Diagrams?

[skaterbasist]

I passed my statics course and am currently taking material stength course.

The thing that has been on my head is the fact that, although I know how to do shear and bending moment diagrams... I do not know how to READ them. In other words, the diagrams don't mean anything to me.

For example, in the diagram below, the maximum moment is being developed under what axis? The z-axis perpendicular to the A support or the z-axis perpendicular to the B support?

I'm not even sure if my question makes any sense. It just bugs me to know that I know how to SOLVE these problems and develop the diagrams, but they're practically meaningless to me.

ANY help would be greatly appreciated!

 

[Mapes]

If you know how to make the diagrams, it's just a matter of practice and repetition because you can "read" them just by looking at them.

The maximum moment is at the location of the force F, the location of largest value on the bending moment diagram.

 

[viscousflow]

For example, in the diagram below, the maximum moment is being developed under what axis? The z-axis perpendicular to the A support or the z-axis perpendicular to the B support?

Th moment vector points out of plane (perpendicular to the page).

 

[PhanthomJay]

For example, in the diagram below, the maximum moment is being developed under what axis? The z-axis perpendicular to the A support or the z-axis perpendicular to the B support?

The internal bending moment in this example acts about the z axis at the point of application of the load. It is counterclockwise acting on the left part of the beam (vectorially pointing outward), and clockwise acting on the right part of the beam (vectorially pointing inward), in accordance with Newton's 1st and 3rd laws. By convention, the moment is considered as a positive moment. You should draw a free body diagram of the section of the beam from the left support to just left of the applied load, to prove this yourself, using Newton 1. Then draw a free body diagram of section of the beam from just right of the applied load to the right support, and proceed in a similar manner.