what is the diffrence between flexural moment ant torsional moment on a Beam?

Question

I just want to know the impartance of torsional moment in design of a structure ,because we have to calculate the flexural moment therefore is it necessary to calculate torsional moments in the design of a structure or not?
my question stands for diffrence of two mentioned moments

Answer 1

Well for 1, one is twisting the other is bending. A moment, as we know is a force over a certain particular distance. a flexural moment has a linear distance factor and a torsinal moment uses a radii as its distance factor. As far as its importance, one would have to determine the material used. Many materials will fail far sooner on its flexual moment than its torsional moment such as wood or steel, due to the molecular structure. I would think it would be important to check if in a earthquake prone region or if it is a high structure to check the torsional moment for wind.