I-beam steel, as shown in the name, is a type of steel with cross-section looks like the character “I”.

The inner surface of the upper and lower flanges of the I-beam has a slope, generally 1: 6, which makes the flanges thin outside and thick inside.

As a result, the cross-section characteristics of I-beams in the two main planes are greatly different, and it is difficult to exert the strength in practical applications.

Although there is thicker I-beam in the I-beam steel market, the structure of I-beam has already determined its shortage in torsion resistance.