Hello all

I was wondering if someone could help me clear my understanding regarding the sign convention and terminology related to Bending Moment Diagrams.

The Sign Convention I have been told to use is:-

1) Tension on top means Negative Bending Moment, also called Hogging Moment.
2) Tension on bottom mean Positive Bending Moment, also called Sagging Moment.

I am simply trying to understand what this means in the context of my example below:-

BMD Example.PNG


1) My first question is that using my sign convention which BMD is correct the Blue or the Green?

2) The term Hogging and Sagging do they relate to the deflected shape of the beam (shown in Pink) or the shape of the bending moment diagram?

If anyone can help shed any light then that would be great.

Thank you.