If your steel has a high section modulus it will be harder to bend and can withstand a high moment without having high bending stress. In simple terms, the section modulus is the ratio of bending moment to bending stress for steel. The bending moment that it takes to yield that section equals the section modulus times the yield strength. In the case for bending a steel section it is important to calculate ‘S’ by taking the moment of inertia of the area of the cross section of a structural member – divided by the distance from the neutral axis to the furthest point of the steel section. There are two types of section moduli, the elastic section modulus (S) and the plastic section modulus (Z). Section modulus is a geometric property for a given cross-section used in the design of flexural members.
Bending a steel section that has a larger section modulus than another will be stronger and harder to bend.
Section modulus is the direct measure of the strength of the steel. To determine if a steel section can be curved you need to first determine its section modulus and then see if you have the correct bending equipment.
