First, I-beams.
As the name suggests, I-beams are steel sections with an “I”-shaped cross-section. The inner surfaces of the upper and lower flanges are inclined, typically at a 1:6 ratio, making the flanges thinner on the outside and thicker on the inside. This results in a significant difference in the cross-sectional properties of the two principal planes, making it difficult to fully utilize the steel’s strength characteristics in applications. Although thicker I-beams have appeared on the market, the structure of the I-beam inherently limits its torsional resistance. Ordinary and lightweight I-beams, due to their relatively high and narrow cross-sections, have significantly different moments of inertia about the two principal axes, greatly limiting their application range. The selection of I-beams should be based on the requirements of the design drawings.
Second, H-beams.
H-beams are widely used in modern steel structure construction. They differ from I-beams in several ways. First, they have flanges; second, the inner surfaces of the flanges are not inclined, and the upper and lower surfaces are parallel. H-beams have significantly better cross-sectional properties than traditional I-beams, channel steel, and angle steel. H-beams are an economical and efficient profile with a more optimized cross-sectional area distribution and a more reasonable strength-to-weight ratio. They are named for their cross-section resembling the letter “H”. The two outer edges of an H-beam are straight, without any slope. This makes welding and splicing H-beams simpler than I-beams, resulting in better mechanical properties per unit weight and saving considerable materials and construction time. H-beams are an economical steel profile widely used in industry, construction, bridges, oil drilling platforms, and primarily as beams and columns in industrial and civil structures. While I-beams have good resistance to direct compression and tension, their narrow flanges limit their torsional resistance. H-beams, on the other hand, offer the opposite advantages. Each has its own strengths and weaknesses.
Third, the difference between H-beams and I-beams.
H-beams, whether standard or lightweight, have relatively high and narrow cross-sections, resulting in a significant difference in inertia between their two principal axes. Therefore, they are generally only suitable for components subjected to bending within their web plane or for forming lattice-type load-bearing members. They are unsuitable for axially compressed members or members subjected to bending perpendicular to the web plane, greatly limiting their application.
H-beams, on the other hand, are high-efficiency and economical cross-section profiles (others include cold-formed thin-walled steel and profiled steel sheets). Their rational cross-sectional shape allows for greater efficiency and improved load-bearing capacity. Unlike standard I-beams, H-beams have widened flanges, and their inner and outer surfaces are usually parallel, facilitating connections with other components using high-strength bolts. They come in a reasonable series of sizes and models, making them convenient for design selection.
H-beams have flanges of uniform thickness and come in rolled sections as well as composite sections composed of three welded plates. I-beams are all rolled sections. Due to inferior manufacturing processes, the inner edges of the flanges have a 1:10 slope. The rolling of H-beams differs from that of ordinary I-beams, which only use one set of horizontal rolls. Because their flanges are wider and have no slope (or a very small slope), an additional set of vertical rolls is required for simultaneous rolling. Therefore, their rolling process and equipment are more complex than ordinary rolling mills. The largest rolled H-beam height that can be produced domestically is 800mm; anything exceeding this must be a welded composite section.
Applications: I-beams have small side lengths and large heights, and can only withstand forces in one direction. H-beams have deep grooves and large thicknesses, and can withstand forces in two directions. With the development of steel structure buildings, I-beams alone are insufficient; even thickened I-beams are prone to instability when used as load-bearing columns. I-beams can only be used for beams, while H-beams can be used for load-bearing columns in structures.
Weight: H-beams are an economical section steel with superior cross-sectional mechanical properties compared to I-beams. They are named for their cross-sectional shape, which resembles the letter “H”. Hot-rolled H-beams have wider flanges, greater lateral stiffness, and stronger bending resistance than I-beams. For the same specifications, H-beams are lighter than I-beams.
Post time: May-06-2026