Abstract: A damped reinforced joint for a beam-column connection is provided for improving the resistance of steel-framed buildings against progressive collapse. Prestressing cables extend across each joint, and each prestressing cable is partially encased within a bent pipe. Each bent pipe may have multiple bends, forming a rippled or undulating shape. The prestressing cables strengthen the connections in the joints, and the bent pipes provide damping for dissipation of seismic energy and the like, thus improving resistance to earthquakes and other seismic, vibratory and/or shock events to the building frame.

Abstract: The strengthening system for beam-column connections in steel frame buildings to resist progressive collapse helps to mitigate progressive collapse in the event of accidental column loss by using a system of rippled steel plates reinforcing the beam-column connection. Various configurations of rippled steel plates are provided to connect in-plane and transverse beams at a joint. In the event of severe damage caused to a column of a steel framed building, the upper joints of the damaged column undergo downward movement. The rippled plates at the joint straighten during the initial downward movement, and resist further downward movement after complete straightening of the ripples. This helps in the development of catenary action in steel beams. The proposed system is simple, fast to construct, demountable, and easy to repair/replace after damage caused by blast loads.