轴压比对不同类型ECC框架节点抗震性能影响

Axial compression ratio effects to the seismic behaviour of different ECC frame joints

对低周循环荷载下框架节点位移延性系数μ影响因素进行分析,指出轴压比是影响框架节点延性的主控因素。以ECC框架节点中十字型节点和T型节点抗震性能试验为原型,基于有限元软件ABAQUS中CDP模型建立框架节点计算模型,并与试验结果比较,验证了计算模拟的可靠性。基于此,建立轴压比分别为0.3,0.5,0.7和0.9的二级抗震等级下的ECC框架节点计算模型,研究轴压比对不同类型ECC节点抗震性能的影响。结果表明:轴压比对ECC框架节点抗震性能影响明显,十字型及T型节点的耗能能力、刚度退化及位移延性系数与轴压比(0.5-0.9)呈负相关,其构件破坏形态为延性破坏;而在同一轴压比(0.3-0.7)和加载制度下,T型节点的抗震性能要优于十字型节点,位移延性系数增加4.1%-35.1%。为了保证十字型、T型框架节点的抗震性能,建议ECC框架节点设计轴压比应控制在0.5左右。

It is pointed out that the axial compression ratio is the main factor affecting the displacement ductility coefficientμof frame joints.Taking the seismic performance test of T shaped and cross shaped ECC frame joints as the prototypes,the calculation model of frame joints is established based on the CDP model in the finite element software ABAQUS,and the reliability of the calculation simulation has been verified by comparing with the test results.Based on this,the calculation models of ECC frame joints with axial compression ratio of 0.3,0.5,0.7 and 0.9 are established to study the influence of axial compression ratio n on seismic performance of different types of ECC joints.The results show that:the axial compression ratio has a significant impact on the seismic performance of ECC frame joints;the energy dissipation capacity,stiffness degradation and displacement ductility coefficient of T shaped and cross shaped joints are negatively correlated with the axial compression ratio(0.5-0.9),and the failure mode is ductile failure;while under the same axial compression ratio(0.3-0.7)and loading history,the seismic performance of T shaped joints is better than that of cross shaped,and the displacement ductility coefficientμincreases by 4.1%-35.1%.In order to ensure the seismic performance of ECC frame joints,it is suggested that the axial compression ratio should be controlled at about 0.5.