The state prohibits the "slimming" processing of steel bars. When straightening by cold drawing method is adopted on site, the specification stipulates that it is not controlled by diameter, but limited by cold drawing rate, and the round steel is not more than 4%, and the ribbed steel bar is not more than 1%. See article 5.3.3 of Code for Construction of Concrete Structure Engineering (GB50666-20 1 1).