I-beam, the inner surfaces of the upper and lower flanges have an inclination, generally 1:6, which makes the flanges thin on the outside and thick on the inside. This results in a huge difference in the cross-sectional properties of the I-beam on the two main planes. It is difficult to exert the strength characteristics in application. Although thickened I-beams have also appeared on the I-beam market, the structure of the I-beam has determined its shortcomings in torsional resistance.
H-shaped steel is a widely used profile in today’s steel structure buildings. It has many differences compared with I-beam. The first is the flange, and secondly the inner surface of the flange has no inclination, and the upper and lower surfaces are parallel. The cross-sectional properties of H-shaped steel are significantly better than traditional I-beam, channel steel and angle steel.
H-shaped steel is an economical cross-section and high-efficiency profile with more optimized cross-sectional area distribution and more reasonable strength-to-weight ratio. It is named because its cross-section is the same as the English letter “H”. The two outer edges of the H-shaped steel have no slope on the inner side and are straight. This makes the welding and splicing of H-beams easier to operate than I-beams, has better mechanical properties per unit weight, and can save a lot of materials and construction time.
The I-beam section can withstand direct pressure well and can withstand tension, but the cross-section size cannot withstand torsion due to the narrow wing plate. H steel is the opposite, both have their own advantages and disadvantages.
Differences and uses of H-beam and I-beam
1. Whether I-shaped steel is ordinary or light, due to the relatively high and narrow cross-sectional dimensions, the moment of inertia of the two main sleeves of the cross-section is quite different. Therefore, it can generally only be used directly on its web. It is not suitable to use axial compression members or members that are perpendicular to the web plane and are curved, which greatly limits its application range.
2. H-shaped steel is an efficient and economical cutting profile (others include cold-formed thin-walled steel, profiled steel plates, etc.). Due to their reasonable cross-sectional shape, they can make the steel more efficient and improve its cutting capacity. Being different from the ordinary I-shaped steel, the flange of the H-shaped steel is widened, and the inner and outer surfaces are usually parallel, which makes it easier to connect to other components with high-strength bolts. Its size constitutes a reasonable series with complete models, which is convenient for design and selection.
3. The flanges of H-shaped steel are all of equal thickness, including rolled sections and combined sections composed of three welded plates. 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-beam steel, which only uses one set of horizontal rollers. Because its flange is wide and has no slope (or the slope is very small), it is necessary to add a set of vertical rollers for rolling at the same time. Therefore, its rolling process and equipment are more complex than ordinary rolling mills. The maximum height of rolled H-shaped steel that can be produced in China is 800mm. If it exceeds the height, it can only be welded and combined.
4. The I-beam has a small side length and a large height, and can only withstand force in one direction. The H-shaped steel channel is deep and thick, and can withstand forces in both directions.
5. With the development needs of steel structure buildings, only I-beams are not enough. Thickening I-beams will easily cause instability when used for load-bearing columns.
6. I-beams can only be used for beams, while H-beams can be used for load-bearing columns of structures.
7. The flange of I-beam is a variable wearing surface, which is thicker against the web and thinner on the outside; the flange of H-shaped steel is an equal wearing surface.
8. HW HM HN H is the general name for H-shaped steel. H-shaped steel is welded; HW HM HN is hot-rolled.
9. HW is an H-shaped steel whose height and flange width are basically equal; it is mainly used for steel core columns in reinforced concrete frame structure columns, also called stiff steel columns; it is mainly used for columns in steel structures.
10. HM is an H-shaped steel whose height to flange width ratio is roughly 1.33~~1.75; mainly used in steel structures: used as steel frame columns and frame beams in frame structures that bear dynamic loads; for example: equipment platforms.
11. HN is an H-shaped steel whose height to flange width ratio is greater than or equal to 2; it is mainly used for beams; the use of I-shaped steel is equivalent to that of HN-shaped steel.