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Classification

I-beams are mainly divided into ordinary I-beams, light-duty I-beams and wide-flange I-beams. According to the height ratio of the flange to the web, it is divided into wide, medium and narrow wide flange I-beams. The first two production specifications are 10-60, that is, the corresponding height is 10 cm-60 cm. At the same height, the lightweight I-beam has narrow flanges, thin webs and light weight. The wide-flange I-beam is also called H-beam, and its cross-section is characterized by parallel legs and no slope on the inner side of the legs. It belongs to economic section steel, which is rolled on a four-high universal rolling mill, so it is also called "universal I-beam". Ordinary I-beams and light-duty I-beams have become national standards.

Pass design

The specification of I-beam is expressed in centimeters of waist width. For example, No. 10 I-beam has a waist width of 10cm. The types of I-beams include hot-rolled ordinary I-beams, light I-beams, and wide parallel-leg I-beams (H-beams). The waist width of hot-rolled ordinary I-beam in my country is 100～630mm, expressed as No.10～No.63, and the slope of the inner side wall of the leg is 1:6. The pass system for rolled I-beams includes a straight-rolled pass system, an oblique-rolled pass system and a mixed pass system. In addition, I-beam steel can also adopt special rolling method.
(1) Straight rolling pass system. The straight rolling pass system refers to a pass system in which the two opening legs of the I-beam pass are on the same side of the roll axis at the same time, and the waist is parallel to the roll axis.
The advantages are that the roller has small axial force, small axial movement, no need to work inclined plane, and the hole pattern occupies a small length of the roll body. Under the condition of a certain length of the roll body, it can be equipped with more holes.
(2) Cross-rolling pass system. This type of pass system means that the two open legs of the I-beam pass are not on the same side of the waist at the same time, and the waist has an angle with the horizontal axis.
(3) Mixed hole type system. According to the characteristics of rolling mills and products, in order to give full play to the advantages of their respective systems and overcome their shortcomings, a mixed pass system is often used, that is, a combination of two or more systems. For example, the finished hole and the front hole of the finished product adopt straight-leg oblique rolling pass system, and other pass patterns adopt the curved-leg oblique rolling system; or the rough rolling hole adopts the straight rolling system, and the last 3 to 4 finishing holes adopt straight-leg oblique rolling hole, etc. .
(4) Special rolling method. When it is difficult to roll the required I-beam by the usual rolling method for some reason, a special rolling method can be used to make full use of the techniques of uneven deformation and pass design. For example, when the billet has a narrow cross-section and a wider I-beam is required to be rolled, the wave rolling method can be used.

Application characteristics

Regardless of whether the I-shaped steel is ordinary or light, because the cross-section size is relatively high and narrow, the moment of inertia of the two main axes of the cross-section is quite different, so it can only be directly used for bending in the plane of its web. Components or form them into lattice-type force-bearing components. It is not suitable to use axial compression members or members that are perpendicular to the plane of the web and bend, which makes the application range very limited. I-beams are widely used in construction or other metal structures.
Ordinary I-beams and light-duty I-beams have relatively high and narrow cross-sections, so the moments of inertia of the two main axes of the cross-sections are quite different, which limits their application range. The use of I-beam should be selected according to the requirements of the design drawings.
The selection of I-beam in the structural design should be based on its mechanical properties, chemical properties, weldability, structural size, etc. to select a reasonable I-beam for use.

Specification model

The specifications are expressed in terms of height × leg thickness × waist thickness, and the number can also be used to indicate the main size of the specification. For example, No. 18 I-beam means an I-beam with a height of 18 cm. For I-beams of the same height, they can be indicated by adding angle codes a, b, or c after the number, such as 36a, 36b, 36c, and so on. It is divided into ordinary I-beam, light I-beam and wide flange I-beam. According to the height ratio of the flange to the web, it is divided into wide, medium and narrow wide flange I-beams. The specifications produced by the first two are 10-60, that is, the corresponding height is 10 cm-60 cm