Experimental Study on Seismic Performance of Composite Concrete Frame BeamEnds With TwoPiece Closed Stirrups

Abstract:

Six concrete frame beamends were tested under low frequency cyclic loading. The seismic behaviors of the specimens with HRB500 highyieldstrength longitudinal rebars and twopiece closed stirrups were analyzed including failure mechanism, hysteretic behavior, skeleton curves, drift ductility and bearing capacity. The results show that the beamend interface and the horizontal interface of composite beam crack and slip，which results in the pinching of hysteretic loops. At the meantime, the energy dissipation capacity and the bearing capacity of the composite beams are smaller than the castinsitu one. Moreover, the displacement ductility factor of specimens is from 3.6 to 4.5. The bearing capacity of composite beams is similar to the castinsitu one, the average ratio of two is 0.90. However, the ratio of composite beams’ ultimate bearing capacity is 1.31 times of that calculated by the code GB 50010—2010. The specimens’ longitudinal rebars yield before the peak load, and the stirrups of the specimens which are subjected to the diagonaltension failure also yield. The effect of stirrup arrangement and beamend interface type on displacement ductility and bearing capacity is not obvious.