What is the difference between I-beam and H-beam?

It is often asked that the shape of I-beam is similar to that of H-beam. How to choose it in practical application? Many people who have been engaged in the construction industry for many years can not explain in detail.

Here is a detailed answer for you: many people think that I-beam is a domestic name and H-beam is a foreign name. In fact, this cognition is wrong. H-beam and I-beam are different in shape, as shown in the following figure:

As the name indicates, I-beam is an I-shaped section steel. The inner surface of the upper and lower flanges has an inclination of 1:6, which makes the outer flange thin and the inner flange thick. Therefore, the section characteristics of the I-beam in the two main planes are very different, and it is difficult to give full play to the strength characteristics in application. Although the thickened I-beam has also appeared in the I-beam market, the structure of the I-beam has determined its torsional performance.

H-section steel is a kind of economic section high-efficiency profile with more optimized section area distribution and more reasonable strength weight ratio. It is named because its section is the same as the English letter “H”. The section characteristics of H-beam are obviously better than those of traditional I-beam, channel steel and angle steel. H-section steel is a widely used profile in steel structure buildings. It is different from I-section steel. The first is the flange, and the second is that the inner surface of the flange has no inclination, and the upper and lower surfaces are parallel. The inner sides of the two outer edges of H-shaped steel are straight without inclination. This makes the welding and splicing of H-section steel simpler than that of I-section steel, with better mechanical properties per unit weight, and can save a lot of materials and construction time.

The section of I-beam is good under direct pressure and resistant to tension, but the section size is too narrow due to the flange plate, so it can not resist torsion. On the contrary, H steel has its own advantages and disadvantages.

The difference between H-beam and I-beam and their application

  1. I-shaped steel, whether ordinary or light, is relatively high and narrow in section size, so there is a large difference in the moment of inertia between the two main sleeves of the section. Therefore, it can only be directly used for members subject to bending in the plane of their webs or formed into lattice load-bearing members. It is not suitable for axial compression members or members with bending perpendicular to the plane of the web, which makes it very limited in the scope of application.
  2. H-section steel belongs to high-efficiency and economic cutting profile (other cold-formed thin-wall section steel, profiled steel plate, etc.). Due to the reasonable section shape, they can make the steel more efficient and improve the cutting capacity. Different from the ordinary I-shape, the flange of H-shaped steel is widened, and the inner and outer surfaces are usually parallel, so it is easy to connect with other components with high-strength bolts. Its size composition is reasonable and its models are complete, which is convenient for design and selection. (except for I-shaped steel for crane beam)
  3. The flanges of H-beam are of equal thickness, including rolled section and combined section composed of three plates welded. All I-beams are rolled sections. Due to poor production process, the inner edge of the flange has a 1:10 slope. The rolling of H-beam is different from that of ordinary I-beam, which only uses a set of horizontal rolls. Because its flange is wide and has no inclination (or the inclination is very small), it is necessary to add a group of vertical rolls for rolling at the same time. Therefore, its rolling process and equipment are more complex than ordinary mills. The maximum height of rolled H-beam that can be produced in China is 800mm, which exceeds that of welded composite section.

According to the national standard of hot rolled H-section steel (gb/t11263-1998), H-section steel is divided into three categories: narrow flange, wide flange and steel pile, and their codes are Hz, HK and Hu respectively. Narrow flange H-shaped steel is suitable for beams or bending members, while wide flange H-shaped steel and H-shaped steel piles are suitable for axial compression members or bending members. Compared with H-section steel, W, IX and iy of I-section steel are not as good as H-section steel under the premise of equal weight.

  1. the side length of I-beam is small and the height is large, so it can only bear the force in one direction.
  2. H-shaped steel groove is deep and thick, and can withstand forces in two directions.
  3. with the development of steel structure buildings, only I-steel is not enough, that is, thickened I-steel, which is easy to lose stability when used for bearing columns.
  4. the I-beam can only be used for the beam, while the H-beam can only be used for the bearing column of the structure.
  5. H-section steel is an economical section steel with better mechanical properties than I-section steel. It is named because its section shape is the same as the English letter “H”. The flange of hot rolled H-beam is wider than that of I-beam, with larger lateral stiffness and stronger bending resistance. Under the same specification, H-beam is lighter than I-beam. Manufacturing principle wechat, with good content, deserves attention.
  6. the I-steel flange is thick near the web of the variable wearing surface and thin outside; The flange of H-shaped steel is equal wearing surface.
  7. HW HM HN h is the general name of H-section steel, which is welded; HW HM HN is hot rolled.
  8. HW is the height of H-shaped steel and the width of flange are basically the same; It is mainly used for steel core column in reinforced concrete frame structure column, also known as rigid steel column; It is mainly used for columns in steel structures.
  9. HM is the ratio of H-beam height to flange width, which is approximately 1.33~~1.75; Mainly used in steel structure: used as steel frame column, and used as frame beam in frame structure bearing dynamic load; For example: equipment platform.
  10. HN is the ratio of H-beam height to flange width greater than or equal to 2; Mainly used for beams; I-beam is equivalent to HN section steel.

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