Research On Mechanical Performance Of K-joint Plane Truss Structure

As an important part of the structure, joints directly affect the mechanical performance of the structure, such as affecting the safety and use of the structure. It is specifically showed that the deformation of the structure, internal force of the members and joints are changed, therefore, the research on mechanical performance of the joints is particularly important. Different factors (namely chord member diameter D, chord member wall thickness T, bracing member diameter d, bracing member wall thickness t, the angle θ between chord member and bracing member)in uni-planar K-joints are studied in the thesis, which influence the mechanical performance of the joints. By using numerical fitting method,the joint stiffness formula is obtained. Plane truss calculation program is obtained by using FORTRAN language, based on the Beam-Column theory. It is showed that mechanical performance of the K-joint affects the mechanical performance of plane truss by using obtained program and software SAP2000 to comparatively analyze the structure. The following work is done in this thesis:(1)Finite element analysis model of uni-planar tubular K-joint is established by using the finite element software ANSYS. When the joints are applied the force and moment to, rotational deformation will change with the different chord member diameter D, chord member wall thickness T, bracing member diameter d, bracing member wall thickness t, the angle θ between chord member and bracing member. The stiffness formula of uni-planar tubular K-joint is obtained with a large number of numerical fitting to the calculation results.(2)Three foreign classification systems of the rigid connections, semi-rigid connections and hinged connections are introduced in the thesis. By analyzing the uni-planar K-joints, a new classification system which is only suitable to uni-planar tubular K-joint is created based on EC3 classification system.(3)Based on Beam-column theory, the calculation program is compiled which is suitable to calculate the plane truss.(4)It makes Analysis on the two calculation examples of plane truss. The joints of the former one are suitable to hinged joints and the joint stiffness must be considered in the last one according to Code for Design of Steel Structure. By analyzing the two examples, the results show:the program SEASF is applicable to calculate and analyze the plane truss; The stiffness of the joints makes little influence on the vertical displacement of the joint and axial force of the members, so the stiffness of the joint in truss can be ignored when calculating the plane truss; The stiffness of the joints greatly impacts the rod ends moment of the chord member in plane truss.