空间网壳相贯节点受力性能有限元分析

Finite element analysis on behavior of spatial latticed mutually intersecting connections

为研究空间网壳相贯节点的受力性能,采用有限元软件ABAQUS建立非线性杆系、实体有限元模型,深入探讨了圆筒相贯、直接相贯两种不同相贯形式节点在轴力、弯矩、剪力复合作用下的复杂应力、变形分布以及应力集中现象;利用两种不同方式,对节点域初始刚度进行评价;计算了节点的承载能力以及安全储备,并探讨了改进节点性能的设计方法。有限元分析结果表明:两种连接形式在应力、变形、承载力等方面基本一致,极限荷载约为设计荷载的2.04倍,具有较大的安全储备;圆筒相贯节点应力集中现象较直接相贯节点有一定缓解,应力集中现象可能会导致局部屈服,存在安全隐患,可通过加厚相贯区域、在此区域进行倒角处理等措施予以解决;圆筒相贯节点比直接相贯节点刚度大,直接与圆筒相连的杆件比既与圆筒相连又与旁边杆件相连的节点刚度大,根据欧洲规范的分类方法以及与杆系模型对比分析,两种形式节点在工程中可以视为刚性连接。

In order to study the behavior of spatial latticed mutually intersecting connections, beam element model and solid finite element model of ABAQUS were adopted. The stress ,deformation distribution and the stress concentration phenomenon were discussed for both the cylindrical intersecting connection and directly intersecting connection under the axis force, bending moment and shear force ; two different ways were used to evaluate the initial stiffness of the connection region; the capacity and safety reserves were calculated and the method to improve performance of the connections was discussed. The results show that ： two kinds of connections basically have the same distribution of the stress, deformation, bearing capacity etc. ; the limited load is about 2.04 times of the design load with greater security reserve. Stress concentration phenomenon of cylindrical intersecting connection is less than the directly intersecting one. The stress concentration phenomenon may cause local yields which leads to potential safety hazard. This problem can be solved by thickening intersection region or chamfering processing. The initial stiffness of cylindrical intersecting connection is larger than the directly intersecting one and the stiffness of the one directly connected to the cylinder is larger than the one connected to both cylinder and adjacent beams. According to both the European standard classification method and the comparative analysis of the beam element model, two types of connections can be regarded as rigid connections in engineering.