Parametric Analysis And Cable Force Optimization Of Single Layer Spoke Structures

As a self-equilibrium system, the single layer spoke structure exhibits the characteristics of small strain and large displacement. The shape of the structure is saddle-shaped, and the structure has the advantage of light-weight, elegant appearance and excellent transparency, which is suitable for construction of large-span stadium. Recently the spoke structure has been applied in Jaber Al-Ahmad International Stadium for the first time. This new type of structure was studied in details in this paper, and the main research results are as follows:(1) Form-finding analysis and load analysis of the single layer spoke structure were carried out, and the relationship between some parameters was further analyzed. The formula for calculating the ratio of cross-sectional area of circumferential cable to radial cable was also summarized. In shape-finding process of the single layer spoke structure, convergence can be realized easily by using this formula. Therefore, form-finding problems of this type of structure can be solved. The static behavior under different load cases was studied, and the effect of outer ring and secondary hoop cable on the structure was analyzed in detail. The whole analysis of the structure was also carried out in this paper.(2) The impact of rise-span ratio, sag-span ratio, the size of internal and external ring as well as the ratio of semi-minor axis to semi-major axis of ellipsoid on the single layer spoke structure was analyzed and discussed. The difference between the single layer spoke structure and the double layer spoke structure was thoroughly analyzed, and the formula was derived.(3) Optimization analysis of the single layer spoke structure based on genetic algorithm was done, and it adopted stiffness, steel consumption and strain energy as objectives. The single-objective and multi-objective optimization were completed by programing which used MATLAB to call the ANSYS general program. The optimization analysis with different objectives was conducted on the premise that deflection and cable force met the prescribed limits.(4) The deflection of the single layer spoke structure is affected greatly by external load, and this is why the defect exists. Great pre-stressing is needed to satisfy the deflection requirements of the specification. Structural optimization was carried out for the original design scheme in this paper. The result indicates that the new scheme (add additional cables) do not increase the steel consumption, and the deflection is more likely to meet requirements.