The effect of impact load on steel frames under fire conditions

To protect structures and save lives from destruction, a proper understanding of how impact load behave and act on structures is essential. On the other hand, steel structures are very sensitive to heat. Impact load and fire in steel structures can cause progressive failure in steel structures. Due to the fact that impact load is sometimes associated with fire, so in this study the effect of impact load on steel frames under fire conditions was investigated. For this purpose, the eight-story three-span steel frame is modelled and subjected to non-linear dynamic analysis by finite element method under impact load simultaneously with fire, and the results in terms of resistance, energy dissipation, deformation and failure in the structure are evaluated and compared. According to the results of this study, applying heat to the structure under the impact load will make the condition of the structure more critical. The results of this study show that applying heat to the steel frame will reduce the shear capacity and energy dissipation of the structure and increase the deformation and the potential for progressive failure in the structure. Applying temperature of 200 to 800 ° C on the steel bending frame will reduce the shear capacity and energy dissipation of the steel bending frame by 8 to 96% and 5.5 to 85%, respectively compared to the steel frame under ambient temperature.