Question

 What is meant by bending moment? Calculate the bending moment of a thin uniform bar of rectangular and circular cross-sections.  

Answer 1

A bending moment is the reaction induced in a structural element when an external force or moment is applied to the element, causing the element to bend.

Bending moment of a thin uniform bar of rectangular and circular cross-section

Bending moment of a thin uniform bar of rectangular cross-section:

$$M=\frac{bd^3}{12R}$$

Bending moment of a thin uniform bar of circular cross-section:

$$M=\frac{\pi Yr^4}{4R}$$