Numerical investigations of fire-resistant steel welded I-section columns under elevated temperatures

Abstract

Based on the experimental investigations on compressive buckling behavior of fire-resistant steel columns subjected to elevated temperatures, the numerical analysis models were established and validated by the experimental results of 12 fire-resistant steel columns and 15 conventional steel columns. The parametric analysis was performed to examine the influence of cross-section types, axial load ratios, normalized slenderness ratios, initial imperfections, residual stress and temperature elevation procedure on critical temperatures of fire-resistant steel columns. The parametric analysis indicated that: (1) The critical temperatures increased with decreasing axial load ratios and slenderness ratios; (2) The fire resistance of column with higher axial load ratios and middle slenderness ratios were more sensitive to the residual stress and initial imperfections; (3) Cross-section size and temperature elevation curve variations had less influence on critical temperatures. Furthermore, a total of 1674 numerical simulations were compared with the results determined from the current standards. It was found that provisions in Chinese GB 51249 and European EC 3 tended to overestimate the compressive buckling coefficient while underestimate the critical temperature, when applied to fire-resistant steel columns. Based on Perry-Robertson formula and EC 3 critical temperature formula, the fire resistance determination methods were proposed to facilitate the engineering application of the fire-resistant steel. The proposed methods were proved to meet both safety and economic requirements of structural design.