两层两跨现浇柱叠合梁框架抗震性能试验研究

以六层现浇柱叠合梁框架底部两层为原型,通过一榀1/2比例的两层两跨现浇柱叠合梁框架低周反复荷载试验,对其受力过程、破坏形态、破坏机制、恢复力模型、变形恢复能力、位移延性、滞回特性、刚度退化、耗能能力等进行了较系统的研究。研究表明:参照现浇混凝土框架抗震设计方法设计的现浇柱叠合梁框架实现了强柱弱梁、强节点弱构件的设计目标;框架的破坏机制为混合机制,即塑性铰首先在一层梁端出现,在一层梁端出现3个塑性铰后柱端出现塑性铰,试件以柱脚混凝土压溃、柱内纵筋压曲外露为破坏标志;在试件受力全过程中,节点核心区箍筋一直处于弹性状态;框架整体及层间的滞回曲线均较为饱满,表明现浇柱叠合梁框架具有良好的耗能能力;框架正、反向的整体位移延性系数分别为5.1和4.2,表明其在低周反复荷载下具有较好的位移延性;得到了四折线型的框架水平荷载-侧移恢复力模型。

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.