Can't Tell the Difference Between I-Beam and H-Beam?

People often ask that I-beams and H-beams have similar shapes. How to choose them in practical applications? Many people who have been in the construction industry for many years cannot explain it in detail.

Here is a detailed answer for everyone: Many people think that I-beam is the domestic name and H-beam is the foreign name. In fact, this perception is wrong. H-beam and I-beam are different in shape.

I-beam

I-beams are mainly divided into ordinary I-beams, light I-beams and wide-flange I-beams. According to the height ratio of flange to web, it is divided into wide, medium and narrow wide flange I-beams. The first two are produced in sizes 10 to 60, which means the corresponding height is 10 to 60cm.

At the same height, lightweight I-beams have narrow flanges, thin webs, and light weight. Wide-flange I-beam is also called H-beam. The cross-section feature is that the legs are parallel and there is no slope on the inside of the legs. It is an economical section steel and is rolled on a four-roll universal rolling mill, so it is also called "universal I-beam". Ordinary I-beams and light I-beams have formed national standards.

As the name suggests, the I-beam is an "I"-shaped cross-section steel. The inner surfaces of the upper and lower flanges have an inclination, usually 1:6, which makes the flanges thin on the outside and thick on the inside, thus causing the I-beam to be in two places. The cross-sectional properties of the main planes vary greatly, making it difficult to utilize the strength properties of steel in applications.

Although thickened I-beams have also appeared in the I-beam market, the structure of the I-beam has determined its shortcomings in torsion resistance.

H-beam

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".

Since all parts of H-shaped steel are arranged at right angles, H-shaped steel has the advantages of strong bending resistance in all directions, simple construction, cost saving and light structural weight, and has been widely used.

H-beam is a widely used profile in steel structure buildings today. 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.

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; the opposite is true for H-beam steel, both of which have their own advantages and disadvantages.

Differences and usage instructions between H-beam and I-beam

1. Whether I-shaped steel is ordinary or light, due to the relatively high and narrow cross-section size, the moment of inertia of the two main axes of the cross-section is quite different. Therefore, it can generally only be used directly on its web plane. Internally bent members may be formed into lattice-type stress-bearing members.

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 cross-section 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.

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 easy to connect with other components with high-strength bolts. Its size constitutes a reasonable series with complete models, making it easy to design and select (except I-shaped steel for crane beams).

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-beams, which only use a set of horizontal rollers. Because its flange is wide and has no slope (or a very small slope), 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.

5. The H-shaped steel channel is deep and thick, and can withstand forces in both directions.

6. 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.

7. I-beams can only be used for beams, while H-beams can be used for load-bearing columns of structures.

8. H-shaped steel is an economical cross-section steel with better cross-section mechanical properties than I-beam. It is named after its cross-section shape is the same as the English letter "H". The flange of hot-rolled H-beam is wider than that of I-beam, has greater lateral stiffness and stronger bending resistance. Under the same specifications, H-shaped steel has a lighter weight than I-shaped steel.

9. The flange of I-shaped steel has a variable cross-section, which is thicker on the web and thinner on the outside; the flange of H-shaped steel has a constant cross-section.

10. HW, HM, and HN are the general names for H-shaped steel. H-shaped steel is welded; HW, HM, and HN are hot-rolled.

11. 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.

12. 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: device platform.

13. HN is an H-shaped steel whose height to flange width ratio is greater than or equal to 2, and is mainly used for beams; the use of I-shaped steel is equivalent to that of HN-shaped steel.