Abstract
In order to increase the earthquake-resistance of high-rise buildings, the steels used must possess strong consistency in plastic deformation, due to low yield-strength ratio. Therefore, the yield-strength ratio is an important parameter to judge the earthquake-resistance of the steels. The experiments of controlled rolling and controlled cooling for different steel grades were carried out. And the effects of chemical composition, ferrite grain size, content of pearlite and bainite and M/A islands on yield-strength ratio were studied and regression formulas for yield and tensile strength were obtained.