I-beams are mainly divided into ordinary I-beams, light 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 specifications produced by the former two are No. 10-60, that is, the corresponding height is 10 cm-60 cm. At the same height, the light I-beam has narrow flange, thin web and light weight. The wide-flange I-beam is also called H-beam. The cross section is characterized by two legs parallel and no slope inside the legs. It is an economical 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 I-beams have formed national standards.