The Design Investigation Of Cable-reinforced Membrane Structures

The whole procedure of cable-reinforced membrane structures design is composed of three parts The first one is form-finding analysis. The aim of this part is to find an initial equilibrium state , the value and distribution of tension force and the geometry of the surface, when the location of the control points are confirmed. The second part is load analysis. Bases on the form-finding, the stress, strain and displacement etc are calculated under loads. Also the problem of membrane drape and cable relaxation should be considered during this procedure. The third part is cutting pattern finding. In this section, the whole surface of membrane structures is divided into several membrane strips. Then the strips are developed into plane to get the cutting pattern on the membrane roll.For form-finding of membrane structures, the common methods mainly indued three theory: nonliner FEM, dynamic relaxation method and force density method. But each method has disadvantages by itself. The synthetical method for form finding of cable-reinforced membrane structures are proposed in this paper. In order to find the minimum surface of membrane structures, firstly the nonlinear finite element method is adopted to get approximate surface, then the dynamic relaxation method is used on the approximate surface to get an accuracy surface. For cable-reinforced membrane structures, gravity is taken into account to find the equilibrium surface. Similarly, the approximate surface is obtained without gravity by the nonlinear element method, then the equilibrium surface is obtained considering gravity by the nonlinear element method. Numerical studies show that the synthetical method proposed in this paper can solve successfully the form finding problems of cable-reinforced membrane structures.A new technique of controlling mesh distortion is presented during the form-finding of membrane structures by dynamic relaxation method. In the course of form-finding, triangle plate element was applied . The damp which was proportion to the velocity of the edge deformation between the two nodes of element was introduced. The node force corresponding to damp was used to control the mesh distortion. Numerical studies show that the method proposed by this paper can successfully control the severe distortion of mesh and retain the density of elements during the membrane form-finding when the damp viscosity coefficient is in a limited scale. Especially this method can avoid the sparseness of mesh in the location of lower curvature and have good convergence characteristic.For loads analysis , a new method considering the effect of meterial main axia is proposed using FEM. For hyperboloid and highpoint shape membran structures, the influence of different parameter to the character of the structures under load is calculated and discussed. The main axid of material should not be neglected.The effect to membrane strucutres of the wind load is prominent. Based on the characteristics of the membrane structures, wind-induced nonlinear coupling dynamic response analysis which can be applied to closed membrane structures is developed and the added air mass the pneumatic stiffness and the acoustical damping of the closed membrane structures are deduced. Applying the method to an aeroelastic model of wind tunnel test, the displacement the velocity and the acceleration of corresponding prototype structure in time domain are obtained. The calculation values have good agreement with the results of the experiment. Numerical studies show that the method proposed in the paper can successfully solve the wind-induced nonlinear coupling dynamic response problems of the closed membrane structures. The present study solves the important problem in the analysis of membrane structures and establishes the foundation of the closed membrane structures design.Cutting pattern finding has three procedures: cutting lines obtainment, curve surface into plane and tension force release. A new method is proposed for geodesic lines generation by nonlinear element method in c...