Advanced Analysis Of Staggered Truss Of Steel Structure

As a novel system of steel structure, the staggered truss system has been analyzed theoretically and applied into some projects internationally.However, no research has been done yet on how to estimate the internal forces considering the structure deformation and the ultimate capacity which are especially important when this kind of system is applied into high-rise buildings. In this thesis, it is the first time to adopt a method of3D analysis to research the staggered truss system concerning material and geometric non-linear. Supported by the National Natural Science Foundation (No.50808096),this thesis is aimed at meeting the needs of structure design, promoting the development of steel staggered truss structure system as soon as possible and filling the gap in the advanced analysis of steel staggered truss structure system.Moreover, popularizing such system is expected.The following works have been fulfilled within this thesis:First of all, based on the general principle of virtual displacement of nonlinear continuum mechanics, the geometric and material stiffness matrices are proposed, several examples show that both of them can give out accurate result. Secondly, some conclusions have been made through the comparison of several examples. In addition, the braced staggered truss system is proposed for the first time as a new type of staggered truss structure system. The system has solved the problem that the lateral stiffness of traditional staggered truss system is weak. Thirdly, a set of equations concerning second-order effects of structure plastic strength, geometric imperfection,residual stresses are proposed to facilitate practical use. The advantage of this simplified design method is that the material and geometric non-linear can be simulated in a convenient way.Based on the research of the staggered truss structure system performance, can draw the following conclusions:1. Longitudinal stiffness of staggered truss system weaker than lateral stiffness significantly. Setting up a support system to ensure longitudinal stiffness meet the specification requirements, improve the structure in the two axis direction stiffness.2. Longitudinal support can obviously reduce the displacement of structure and interstorery draft ratio, increase the longitudinal lateral stiffness effectively, improve the seismic and wind resistance performance of the structure.3. Compared with cross and V shape,the herringbone supportis the best in applicability and economy.4. Most of the members of staggered truss structure are in the condition of axial force. It can give full play to material performance, reduce the weight of the structure, save materials, and reduce the cost of the structure.5. Maximum interlayer displacement Angle of staggered truss structure system have occurred in the bottom of the layers, so the design of staggered truss structure system, should strengthen the layers at the bottom6. The aspect ratio of the structure has great influence in the second-order effect and the ultimate bearing capacity. When the aspect ratio increases, the second order effect increases, ultimate bearing capacity decreased.