The inner and outer sides of the flanges of H-shaped steel are parallel or nearly parallel, and the ends of the flanges are at right angles, hence the name parallel flange I-beams. The web thickness of H-shaped steel is smaller than that of ordinary I-beams with the same web height, and the flange width is larger than that of ordinary I-beams with the same web height, hence the name wide flange I-beams. Determined by the shape, the section modulus, moment of inertia and corresponding strength of H-shaped steel are significantly better than ordinary I-beams of the same single weight. When used in metal structures with different requirements, it shows its superior performance whether it is subjected to bending moment, pressure load, or eccentric load. It can greatly improve the bearing capacity compared with ordinary I-beams and save 10% to 40% of metal. H-shaped steel has wide flanges, thin webs, multiple specifications, and flexible use. It can save 15% to 20% of metal when used in various truss structures. Because its inner and outer flanges are parallel and the ends of the flanges are at right angles, it is easy to assemble and combine into various components, thereby saving about 25% of welding and riveting work, which can greatly speed up the construction speed of the project and shorten the construction period.