Rigidity Of Unstiffened Joints Effect To Global Performace Steel Tubular Structures

In recent years, shells is widely used in stadiums, exhibition halls and other large-span spatial structure. Because tubular joints of construction is convenient and its structure is very simple, tubular joints become the space structure of commonly used form of joints. Joints which has not had reinforcement can not attain the requirement of rigid-joints, so this greatly limits the use of the joints with a single-layer shells. Actually, tubular joints is a semi-rigid joints, and it has a certain bending stiffness. The shells which is used by the semi-rigid joints has a certain carrying capacity, but it is different to the shells which is used by a rigid joints. Therefore, the article choose the Schwedler shells model and research effection of the semi-rigid in shells. Bised on ADINA, the article proposes a new method of simulation, which can accurately simulate the stiffness of joints in structural analysis. The thesis include the following three sections:The first, used the shell unit of the finite element software ADINA to establishe modle of tubular joints, axial-force effects on the properties of tubular joints outside bend surface, which includes the ratio of branch diameter to chord diameter and the ratio of chord diameter to chord thickness. To get on the double nonlinear analysis in different models, the analysis can attain a moment-rotation curve in intersection of joints. Thereby, the article can calculate the bearing capacity and initial stiffness, and analysis its impact of axial force.The second, the article summarize the universal joint stiffness of calculation methods. Based on the finite element software ADINA, the method of simulation the stiffness of joints is put forward, and the moment-curvature beam element is used by simulation of joint stiffness.what is more, with Some typical examples which included the izod architecture and the double pole architecture, the sofeware ADINA is used by research which test the this method of feasibility and provide theoretical support for the follow-up study.The finally, applicated the software ADINA to establish Schwedler shell model, the structure analysis introducted the joint stiffness by the moment-curvature beam element. When the model was build, the article choose the difference of parameters which includes span, rise-span ratio, the cross-section, the form of load distribution, the boundary conditions and so on. It can obtain the effect of different parameters on the structural stability of the semi-rigid shells.