Design equations for evaluating fire resistance of SFRC-filled HSS columns

Computer programs were developed and used to investigate the influence of various factors on the fire resistance of steel hollow structural section columns filled with steel fiber-reinforced concrete. Results from the parametric studies were used to develop simple equations for calculating the fire resistance of steel fiber-reinforced concrete (SFRC)-filled hollow structural section (HSS) columns with circular and square cross sections. The validity of the calculation procedure was established by comparing the calculated fire resistances with those obtained from fire tests on columns. These equations provide a rational and easy-to-use design method for evaluating the fire resistance of hollow steel columns filled with steel fiber-reinforced concrete for any value of the significant parameters that determine it, such as load, cross-sectional dimensions, effective length, and concrete strength. The proposed equations give reasonable estimate of fire resistance for SFRC-filled circular HSS columns; however, the predicted fire resistances can be overconservative for SFRC-filled square HSS columns. Hence, these equations can be used in preliminary design and, where available, the designer should rely on furnace testing when not satisfied with the estimated fire resistance values.