I-beams and H-beams each have their own advantages and disadvantages. I-beams are outstanding in terms of compression resistance and stability, while H-beams are more advantageous in terms of bending resistance and cross-sectional efficiency.
I-beams, whether ordinary or light, have relatively high and narrow cross-sectional dimensions, so the moment of inertia of the two main sleeves of the cross-sectional area is quite different. Therefore, they can generally only be used directly for members that are bent in the web plane or to form lattice-type load-bearing members. It is not suitable for axially compressed members or members that are bent perpendicular to the web plane, which greatly limits its scope of application.
H-beams are efficient and economical cross-sectional profiles (others include cold-bent thin-walled steel, corrugated steel plates, etc.). Due to their reasonable cross-sectional shape, they can make steel perform more efficiently and improve their bearing capacity. Unlike ordinary I-beams, the flanges of H-beams are widened, and the inner and outer surfaces are usually parallel, which makes it easy to connect with other components with high-strength bolts. Its size constitutes a reasonable series, and the models are complete, which is convenient for design and selection.
The flanges of H-shaped steel are of equal thickness, with rolled sections and combined sections composed of three plates welded together. I-beams are all rolled sections. Due to poor production technology, the inner edge of the flange has a slope of 1:10. The rolling of H-shaped steel is different from that of ordinary I-beams, which only uses one set of horizontal rollers. Because its flanges are wide and have no slope (or the slope is very small), a set of vertical rollers must be added for rolling at the same time. Therefore, its rolling process and equipment are more complicated than ordinary rolling mills. The maximum height of rolled H-shaped steel that can be produced in China is 800mm. If it exceeds this, it can only be a welded combined section.
