The effect of fire conditions on reliability of steel beam

In order to study fire behaviors of steel member and the effect of fire conditions on its reliability, fire response of restrained steel beam was implemented by non-linear finite element method. The temperature distribution and deflection curve of beam acquired from numerical simulation are good correlative with ones of experiment. Based on this, the reliability model of steel beam was established using Monte-Carlo method. The effect of stochastic variables in natural fire model on the reliability was discussed by parametric method. The results show that the fire stochastic variables have different effects on sensitivity of beam reliability. The impact of maximum temperature T_m is the most obvious, that of shape constant s_c is minimal. With increasing T_m and s_c, or decreasing the time t_m at which T_m occurs, and increasing the variance of stochastic variables, the reliability of steel beam will descend. When maximum temperature and shape constant were decreased and the time at which maximum temperature occurs was increased, the fire-resistant duration of the beam will be prolonged, which is benefit to improve the fire reliability. The model in this paper is provided a new method for quantitative analysis of stochastic fire reliability and reasonable fire-resistant design.