Differences:
1. The I-beam has a small flange width and a large height, and can only bear force in one direction. The H-beam has a deep groove and thick web, allowing it to withstand forces in two directions. 2. The I-beam can only be used as a beam, while the H-beam is suitable for use as a load-bearing column in structures. 3. The H-beam is an economically efficient section steel with better mechanical properties than the I-beam. It is named for its cross-sectional shape resembling the letter "H." Hot-rolled H-beams have wider flanges, greater lateral stiffness, and stronger bending resistance compared to I-beams. For the same specifications, H-beams are lighter in theoretical weight than I-beams. 4. The I-beam has variable section thickness—the flanges are thicker near the web and thinner at the edges—while the H-beam has uniform flange thickness. Whether ordinary or lightweight, I-beams have relatively high and narrow cross-sections, resulting in a significant difference in the moment of inertia about the two principal axes. As a result, they are generally only suitable for direct use in components that bend within the plane of the web, or when combined into lattice-type load-bearing structures. They are not suitable for axial compression members or components that also bend perpendicular to the web plane, which greatly limits their range of applications. The H-beam is a type of efficient and economical section steel (others include cold-formed thin-walled steel and profiled steel sheets), and due to its rational cross-sectional design, it enables steel to perform more effectively and enhances load-bearing capacity. Unlike ordinary I-beams, the flanges of H-beams are widened, and their inner and outer surfaces are usually parallel, making them convenient for connection with high-strength bolts and other components. Their dimensions form a rational series, with a full range of models, facilitating design and selection. (Except for crane beams, where I-beams are used.)
