progressive collapse evaluation of steel structures considering the effects of uncertainties and catenary action

Various collapse modes have been observed so far in the phenomenon of progressive collapse. this study examines the collapse modes in damaged structures using pushdown analysis for two scenarios of removing interior and exterior columns. a special moment-resisting frame is selected as a structural model. the effect of catenary action is considered under three damage states including light, moderate and severe. in addition, the effect of uncertainty parameters such as yield strength, modulus of elasticity, dead and live loads are investigated on the structural responses using probabilistic analysis. the monte carlo simulation method is used to perform probabilistic analysis. latin hypercube sampling method is used to generate random realizations to achieve good accuracy. then, a sensitivity analysis is performed. the results showed that a more precise and realistic estimation of the structural resistance and collapse modes will be achieved for the structure under progressive collapse when the effect of catenary action and uncertainties are considered. the catenary action effect is more significant when the damage in the structure increases. also, increasing the axial force in the beams causes that the bending moment decreases in the case of moderate damage. the results of sensitivity analysis showed that the yield strength of members is the most effective parameter of uncertainty on changing the axial force demand of the interior column after removing the exterior column.