I-beams are mainly divided into ordinary I-beams, light I-beams and wide flange I-beams. According to the ratio of flange to web height, they are divided into wide, medium and narrow wide flange I-beams. The specifications of the first two are 10-60, that is, the corresponding height is 10 cm-60 cm. At the same height, light I-beams have narrow flanges, thin webs and light weight. Wide flange I-beams are also called H-shaped steels. The cross-section characteristics are that the two legs are parallel and there is no slope on the inside of the legs. It belongs to the 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.