HE A and HE B steel sections have distinct mechanical properties that stem from their design and manufacturing characteristics. HE A sections are designed with a relatively thinner web and flanges compared to HE B sections. This results in a lower overall weight for the same height of the section. Consequently, HE A sections have a slightly lower load - bearing capacity in terms of shear and bending resistance compared to HE B sections.
The difference in dimensions directly affects properties such as the moment of inertia and section modulus. HE B sections, with their thicker webs and flanges, have higher values for these properties. A higher moment of inertia means better resistance to bending, making HE B sections more suitable for applications where large bending moments are expected, such as in the main girders of heavy - duty bridges or the long - span beams of industrial buildings.
The manufacturing process also plays a role. Both types are hot - rolled, but the specific rolling parameters and tolerances may vary to achieve the desired cross - sectional dimensions. Additionally, the chemical composition, although generally conforming to the same steel grade standards, might have slight variations in the content of alloying elements. These variations can influence the strength, ductility, and toughness of the steel, contributing to the differences in mechanical performance between HE A and HE B sections.