Research On Stability Of Single Layer Spherical Lattice Shell With Large Depth-to-Span Ratio

Single layer spherical lattice shell is the most widely used form of spatialstructure in the world. It is widely used in: airports, stadiums, railway stations,exhibition halls, cinemas and theaters. With the development of economy，more andmore single layer spherical lattice shells with large span and huge height appear.Single layer spherical lattice shell safety factor does not apply to such single layerspherical lattice shells with large span and huge height.The purpose of the paper is to study the stability of the single layer sphericallattice shell with large span ratio. In order to improve the stability of the single layerspherical lattice shell, research is made considering the following factors such as: gridlayout, initial defects, span ratio, bearing forms and material nonlinearity. Geometricnonlinear load-displacement curves and double nonlinear load-displacement curvesare acquired, so as to the plasticity reduction factor Cp. Through probability andstatistics methods safety factor K is acquired.Studies have shown that the factor affect the stability of large span ratio ofsingle-layer reticulated shell most is the plasticity of the material. So it is unsuitablejust considering geometric nonlinear, when considering on single layer sphericallattice shell with large span ratio. And high latticed shells are more sensitive thanothers on initial defects. Bearing forms affect little, because the first site of instabilityis the equatorial part.During the analysis on single layer spherical lattice shell with large span ratio,L/300initial defects still need to be considered. The double nonlinear analysis shouldbe carried out considering the plasticity, so as to get load-displacement curves andthe ultimate loads. If only carrying out geometric nonlinear analysis, plasticityreduction factor Cp is much smaller than0.47. Its value is0.2. Therefore, the safetyfactor K should be10, instead of4.2.