Progressive collapse behavior of beam-to-column connections involving flange openings

Abstract

Improving the ductility of the structure to withstand local damage and prevent progressive collapse is critical for steel-frame structures. In this study, a novel principle of beam-to-column connections was developed, which arranged openings at the beam flange to form a flange-opening section (FO). First, experimental investigations were conducted on two FO substructures, considering their deformation capacity, failure modes, internal force evolution, and resistance mechanism development. Second, numerical simulations verified by experiments were conducted to further investigate the number n, distance l, and diameter d of the flange openings, and the results were compared with those of the case that had no weakening of mechanical properties. Third, because some flange openings weakened the mechanical properties of the structure, specimens with V-shaped reinforcing plates (FOV) were studied. The results indicated that the mechanical properties of the FO specimens increased with n, decreased with an increase in d, and increased with l. The mechanical behavior of the new beam-to-column connections using flange openings and reinforcing plates was studied to relocate the plastic hinge, realize a second path, and successfully improve the progressive collapse resistance of the steel frame structure.