| The traditional design method consists of two stages: elastic analysis is used to determine the forces acting on each member of a structural system, whereas inelastic analysis is used to determine the strength of each member treated as an isolated component. However, despite its popular use in the past and present as a basis for design, the approach has major limitations. There is no verification of the compatibility between the isolated member and the member as part of a frame. The individual member strength equations as specified in specifications are not concerned with system compatibility. As a result, there is no explicit guarantee that all members will sustain their design loads under the geometric configuration imposed by the framework. The advanced analysis is actually a kind of second-order elasto-plastic analysis method. It refers to any method that can capture the strength and stability of a structural system and its individual members in such a manner that individual member capacity checks are not required, which simplify the design process.The simple plastic-hinge model based on the finite element theory and the refined plastic-hinge model based on the beam-column theory were derived. The geometric nonlinear, material nonlinear, shear deformation, torsional deformation, initial imperfection and semi-rigid connections were discussed in the paper. Object-oriental program ADANS based on space steel frame advanced analysis theory was compiled using C++ language. The followings were the main contents in detail.Based on the theory of continuous medium mechanics, second-order elastic stiffness matrix of a 3-D beam-column for space steel frames was derived making use of updated Lagrangian formulation, virtual displacement principle and cubic interpolation functions considering shearing effect. Nonlinear effects, such as initial imperfection, shear deformation, warping deformation, dual-direction bending, torsion and axial deformation were considered in element formulation. Based on the Prandtl-Reuss and Drucker theory, the element stiffness matrix considering plastic-hinge occurred on the ends of the element was derived.Spatial beam-column elements with and without initial imperfection were studied. And their stiffness matrixes considering shear deformation effect were derived. For element without the initial imperfection, the effects of residual stress, gradual yield reduced by bending, the couple of bending and torsion were also studied.Moment-rotation relationship of semi-rigid beam-to-column minor axis connections was researched through experimental tests. A new type connection was proposed. The performance of the connection was studied and contrasted with semi-rigid beam-to-column major axis connection.Modified beam element method was used to account for the effect of connection flexibility on the structural behavior. The pin, rigid and semi-rigid connections were discussed.Based on the object-oriented analysis and design conception, the finite element analysis domain was divided into many classes, such as CNode, CNodeMng, CBaseElement, CBaseElePro, CBaseMaterial, CLoad, CLoadGroup, CGlobalElement and lots of inherit classes. Using advanced analysis theories, the spatial steel frame analysis program was complied. Nonlinear analysis adopted Newton-Raphson and general displacement control methods. The problems about finite space rotational properties, some update methods of beam-column element transformation matrix and convergence rules were discussed. The static analytical results of proposed elements were compared fairly well with that of some representative steel frames, and only few proposed elements for each member were needed to achieve acceptable accuracy. The proposed beam-column element has excellent efficiency and will save much time in the analysis of large-scale structures compared to numerically integrated element.Through the data file, the further development of ANSYS was achieved. The program CRSTRESS considering the residual stress effect was compiled, and through which plane and spatial steel frame were studied. Finally, the ultimate strength capacities of an arch steel frame with variable curvatures and variable sectional heights were studied.
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