Improving collapse-resistance performance of steel frame with openings in beam web

Abstract To overcome the shortcomings of the traditional fully welded connection and the connection with openings in the beam web against earthquakes and progressive collapse, a new type of reinforced connection with openings in the beam web (RBWO connection) is proposed. This connection is characterised by M-shaped structural plates arranged inside the upper and lower flanges of the beam end based on the connection with the openings in the beam web. The addition of the M-shaped structural plate is beneficial to the improvement in the initial stiffness, yield load, and ultimate bearing capacity of the structure under cyclic loading. When the M-shaped structural plate is accurately designed, the catenary mechanism is fully developed under the failure of the middle column. The specimen can realize the secondary resistance stage, and the anti-progressive collapse performance of the structure is significantly improved. To improve the role of the M-shaped structural plate in the secondary resistance stage, the expected failure order is sequential fracture of the beam web, beam flange, and M-shaped structural plate at the reduced section of the beam. Finally, the seven design parameters of the RBWO connection are comprehensively analysed and suggested by numerical analysis of three series specimens.