690MPa-yield-strength fire-resistant weather-resistant earthquake-proof construction steel and production method thereof

The invention relates to a 690MPa-yield-strength fire-resistant weather-resistant earthquake-proof construction steel which comprises the following components in percentage by weight: 0.051-0.155% of C, 0.20-0.60% of Si, 1.82-2.55% of Mn, at most 0.008% of P, at most 0.002% of S, 0.081-0.090% of Nb, 0.010-0.025% of Ti, 0.41-0.60% of Mo, 0.08-0.10% of W, 0.0071-0.0095% of Mg and at most 0.0010% of O. The production method comprises the following steps: desulfurizing molten iron; smelting in a converter; carrying out vacuum treatment, and adding the Mg element; carrying out conventional continuous casting, and heating the casting blank; carrying out sectional rolling; and carrying out finish rolling, and cooling for later use. The steel has the following advantages: the chemical components and technique are simple, the yield strength of the steel plate is 690-850MPa, the earthquake-proof property is good (the yield-tensile ratio is at most 0.83), the fire resistance is favorable (the yield strength at 600 DEG C is not lower than 2/3 of that at room temperature), and the corrosion resistance is better than CortenB. Besides, the steel grade has excellent impact toughness and weldability.