Experiments And Finite Element Analysis On Complex Tubular Joints

Hollow section structures have been widely used in the large-span spatial structures due to their good mechanical properties, nice appearance, and relatively low cost. The research on the behavior of joints is one of most important links in design of hollow section structures, since failure of joints may lead to the damage of relevant rod,and the whole structure will be no longer in force. The status of overseas and domestic research is mainly concentrated on uniplanar joints and some simple multiplanar joints, for example spatial KK-joints. While the research on complex spatial multiplanar joints is rare, and all countries have not given the explicit calculation formula for these joints, so research on complex spatial multiplanar joints is to be done.In this paper, the mechanical behavior and bearing capacity of the several joints have been researched with the example of East Hangzhou Railway Station and Huzhou Stadium.In order to provide a reliable basis for the design of the joints of the roof structure in East Hangzhou Railway Station, this thesis have finished experimental research for seven different shaped multiplanar joints East Hangzhou Railway Station, and then conducted comparative analysis of the flashboard on three joints. The result of the experimental research shows that all kinds of joints have enough capacity of bearing load and safety stock, and that the design of joints is safe and reliable. The flashboards in joints influence the mechanical behavior in many aspects, including improving the limit bearing capacity of the joints, changing joint failure mode, improving joint area stress distribution and reducing joint deformation, etc, but these influence can not be generalized.Based on the elastic-perfectly plastic model and Von-Mises yield criterion, the finite element models for joints from the main building of East Hangzhou Railway Station are established with the software ANSYS, and understand the stress distribution, the development of plastic zones and the failure modes of joints which had finished experimental research.Results from finite element modeling of the experiment joints indicate that, the elastic-plastic nonlinear analysis considering large deformations can simulate the mechanical properties of the joints satisfactorily.Finally, some geometry and load effect finite element parametric analysis are conducted to learn the bearing capacity of the joints and failure mechanism of the circular tubular KTX-joint and KTK-joint which are selected from roof structures of Huzhou stadium. It is found that the mainly failure mode of the multiplanar joints is the chord wall plastic failure mode. The analysis results show that, the diameter ratio with chord and web member and the ratio with chord diameter and thickness have greatly influenced the bearing capacity, while the thickness ratio with chord and web member don’t influence it significantly.