ANALYTICAL METHOD AND SHAPE OPTIMIZATION OF SADDLE SINGLE-LAYER ORTHOGONAL CABLE-NET STRUCTURE

The common single-layer orthogonal cable-net structure is formed by the intersection of saddle surface and elliptic cylinder. This structure is widely used in large-scale stadiums and public buildings at home and abroad. A method is proposed to obtain the deformation, internal force and optimal shape of elliptic saddle single-layer orthogonal cable-net structure by using continuous analytical method. In this process, only the one-dimensional equation needs to be solved. The continuous calculation formula of orthogonal single-layer cable-network is deduced by the balance equation and deformation coordination equation, and takes the vertical displacement as the unknown which approximate solution is obtained by Galerkin method. On this basis, it takes the minimum in-plane moment of the outer-ring beam as the optimization objective, takes the sag of the central bearing cable as the optimization variable, and takes the cable force, vertical displacement and rise span ratio as the constraints. And then, it uses the formula for calculating the outer ring bending moment to obtain the optimum structure and the optimization process is given. Finally, a simple example is calculated by the finite element method and analytical method respectively to verify the accuracy of the calculation formulas of displacement, cable force, outer-ring moment and shape optimization results obtained by the analytical method. In the preliminary design stage of the structure, the displacement, stress and optimal shape can be quickly obtained by using this method, which avoids the complicated process of finite element programming and repeated calculation.