钢管混凝土外加强环节点抗震性能有限元分析

钢管混凝土结构节点的抗震性能的研究一直受到人们的重视,低周反复加载试验结果指出,加强环式节点滞回曲线饱满且稳定,但同时也发现,在节点域会出现鼓胀现象.为了解释这一现象,对加强环式节点进行了低周反复加载非线性模拟分析.分析内容包括节点的滞回耗能指标、节点域变形及节点域塑性扩展三部分.研究指出:(1)节点的滞回曲线饱满稳定,耗散系数都在2.0以上,表明节点整体延性很好;(2)腹板焊缝孔开孔过大,节点滞回曲线有不重合现象,可见腹板焊缝孔尺寸需要控制;(3)节点域柱壁有明显的变形,规律与滞回曲线相似,表明节点滞回曲线主要是由柱壁变形而非梁端塑性变形贡献的;(4)在反复荷载作用初期,环板就出现了贯穿的塑性带,而在相隔相当长的荷载循环之后,梁面上才有塑性出现.由于在反复荷载作用下,节点域发生了明显的变形,且在环板上形成贯穿的塑性带.

Finite Element Analysis Seismic Behavior on Exterior Joint of Concrete Filled Steel Tubular

The research of the seismic behavior of Concrete Filled Steel Tubular(CFST) joint has always attracted much attention,the result of cyclic loading indicates that,hysteretic curve of stiffener ring joint shows good plumpness and stability,meanwhile,expansion is observed in joint region.In order to explain this phenomena,nonlinear simulation analysis is applied in cyclic loading of stiffener ring joint.The analysis include hysteretic energy of joint,deformation and plasticity in joint region.The research shows that:(1) hysteretic curve of the joint is plump and stable,with all the dissipation coefficient above 2.0,which is the criterion of good plasticity.(2) The size of web weld hole is larger than requirement,in this case,hysteretic curve of the joint does not coincide,thus the size of the web weld hole must be controlled.(3)obvious deformation is observed in the cylindrical wall of the joint region,the law is similar with the hysteretic curve,which manifests the principle that the hysteretic curve is mainly contributed by the cylindrical wall deformation rather than beam end plasticity deformation.(4)In the initial stage of cyclic loading,run-through plasticity band appears in annular plate,after a long period of cycling loading,the plasticity occurs in the beam.Due to the cyclic loading,significant deformation occurs in the joint region,run-through plasticity also appears,therefore,it is concluded that,stiffener ring joint does not comform with the principle of "strong joint".