There are two common classification methods of steel bars: one is to classify according to the geometric shape of steel bars, and the other is to classify or classify according to the cross-sectional shape of transverse bars and the spacing between bars. For example, steel bars are classified into Type I and Type II in British Standard (BS4449). This classification mainly reflects the grip performance of steel bars. Second, according to the performance classification (grade), for example, according to the current implementation standards in China, rebar is (G B 1499.2-2007), wire is 1499. 1-2008), and rebar is divided into three grades according to the strength grade (yield point/tensile strength); According to Japanese industry standard (Ji SG3 1 12), rebar can be divided into five categories according to its comprehensiveness. British Standard (BS446 1) also stipulates several grades of steel bar performance test. In addition, steel bars can also be classified according to their uses, such as ordinary steel bars for reinforced concrete and heat-treated steel bars for prestressed reinforced concrete.