Experimental study on seismic behavior of two-story two-bay frame with composite beams and cast-in-place columns

This paper presents an experimental study on seismic behavior of a two-story two-bay frame with composite beams and cast-in-place columns,which was modeled from the lower story of a six story prototype residential building.Based on the cyclic loading test,seismic behavior of the test specimen was evaluated in terms of failure modes,failure mechanism,stiffness degradation,energy dissipation capacity,displacement ductility etc.The test results showed that the test frame achieved the design objective of strong column-weak beam and strong joint/weak element.The failure mechanism was a mixed mechanism,and the first plastic hinge occurred at the beam end,and the plastic hinge began to appear at the column end while there were three plastic hinges in first-story beam end;the test was halted due to concrete crushing and buckling of longitudinal bars as a result of plastic hinges at the fixed column end,and the strains of all the joint hoops in test specimen kept in elastic stage.The hysteresis curves of the test specimen were full and exhibited good energy dissipation.The ratio of overall displacement ductility in positive and negative directions was 5.1 and 4.2,respectively,showing good ductility.A four-linear restoring force model was obtained based on the analysis of the hysteresis curves.