Geometrically Nonlinear Static And Dynamic Stability Analysis Of Cylindrical Orthogonal Single-layer Lattice Shell Structures Supported By Four Points

Cylindrical orthogonal single-layer lattice shell structures intersected by two cylindrical shells are new types. The determinant factor of desin for single-layer shell structures is stability but not strength. At present, researches about the static behavior and geometrically nonlinear stability of cylindrical orthogonal single-layer lattice shell structures supported on the rigid roof beam or Fringe truss have been consummate. But researches about this structure supported by four points are most in static behavior and less in geometrically nonlinear static stability. Aimed at this problem, geometrically nonlinear static and dynamic stability are studied in this paper. Based on nonlinear finite element theory, the tangent stiffness matrix in space frames is deducted , the programs of nonlinear static and dynamic stability are compiled. During geometrically nonlinear analysis, the Arc-Length Method is used, the stable equilibrium path is traced. By tracing whole load-deflection path of structures, the whole changing processes are obtained at any specified load levels, which are about structures' strength, stability and stiffness. At last, the static stability critical loads of cylindrical orthogonal single-layer latticed shell structures supported by four points are estimated reasonably. In this paper, the static stability of this structure supported on different forms are calculated and analyzed. At the same time, static stabilities of this structure are analyzed considering different structural parameters, for example the section of the members, ratio of rise to span ,etc. Some useful conclusions for design are given for this struture. During geometrically nonlinear dynamic analysis of the structure in this paper, the acceleration values of seismic loads are adjusted by proportion method, so that the peak value of acceleration answer calculation meet needs. The dynamic responses of cylindrical orthogonal single-layer lattice shell structures supported at four corners are calculated under seismic loads of different acceleration. So the displacements of joints about shell structures are got and the maximal nodes displacement of all structures can be found. The curve of maximum displacement of nodes under dynamic acceleration and curve of displacement history of the nodes of shell structures can be drawn, the dynamic stability critical loads of cylindrical orthogonal single-layer lattice shell structures are estimated throughBudiansky-Roth rule, the curve of node displacements time history and the configuration of the shell structures. And some questions of the structure that should be resolved in the future are discussed.