Fire-induced progressive collapse mechanisms of steel frames with partial infill walls

This paper presents a numerical investigation on progressive collapse mechanisms of steel frames with partial infill walls under fire scenarios using ABAQUS platform. The load redistributions and collapse mechanisms of steel frames subjected to different fire scenarios (edge bay and central bay fires) are studied. The influences of strength, opening percentage and layout of partial infill walls are also analyzed. The results of the numerical analysis indicate that the presence of partial infill walls causes combined tensile force and bending moment at the ends of surrounding beams. The strut action of partial infill walls and the overturning moment imposed by the frame in the collapse bay are identified as load redistribution mechanisms of the steel frame. The steel frame using higher strength steel, more number and lower opening percentage of partial infill walls collapses at higher temperatures. Furthermore, the analyses identify three deformation modes of beams depended on the layout of partial infill walls. Finally, a preliminary design method based on equivalent compressive strut model is proposed with good accuracy, in order to prevent the steel frame with partial infill walls from fire-induced collapse in engineering practice.