## 5 Conclusions  
This paper introduces a new non-bracket construction method for annular cable supported grid structures. First, the characteristics of the structure are discussed. It is essentially a cable truss with the upper flexible cables replaced by rigid grids. The structural stiffness of the self-equilibrium stress system, composed of cable strut system, compression ring, and upper grid, still mainly depends on the tensioned cable net. The integrity of the cable strut system gives this kind of structure a natural foundation for non-bracket construction. The situation where components in the self-equilibrium stress system cannot be constructed as a whole results in great difficulty controlling the structure configuration in the non-bracket process. Based on these characteristics, a new non-bracket construction method for annular cable supported grid structure is proposed. This method utilizes jacks fixed near the radial cable anchor points to reliably and stably lift the cable net, and creatively solves the problem of accurate control of the cable net and grid installation position through the setting of tie-downs. Finally, based on the actual Education City Stadium in Qatar, the new construction method is applied in practice and the whole construction process is simulated in ANSYS finite element software (Version 2019 R1). The following conclusions could can be drawn from the calculation results:  
1. In the early stage of the construction (i.e., construction steps 1-3), the CR and cable net comprise the basic system of the structure. At this time, the pre-tension level in the cable net is still relatively low and the structural flexibility is large, and the excessive deformation and local torsion of the compression ring require special attention. In the actual construction process, it is necessary to analyze the compression ring deformation, local torsion, and other structural responses to improve the cable net traction lifting and tie-down tensioning strategy. In this paper, the original synchronized equally proportioned strategies are adjusted to cumulative sectional strategies according to the analysis results;
2. In the construction process, when the tie-downs come into effect (i.e., construction steps 3-5), the displacement of the tension ring nodes and CR nodes is basically close to 0, which means that the CR and tension ring can basically maintain the design configuration during the whole process of cumulative hoisting of the upper rigid grid, ensuring that the grid can be assembled accurately according to the design size;
3. From construction steps 3 to 5, the CR and cable net configuration, radial cable forces, and structural stress level are all relatively stable, and basically consistent with the corresponding response of the step when the final roof is formed (construction step 43). This indicates that the tie-downs can effectively and accurately simulate the uninstalled components to load on the installed structure before the self-balancing system of the cable supported grid structure is formed, to keep the structure in the designed balance state during the construction process. The stable structural deformation, cable force, and stress levels also indicate that the setting of tie-downs can ensure construction stability and safety when the self-balancing system is not formed;
4. The radial cable force distribution keeps the same trend during the entire construction process, and radial cable forces from step 3 to step 5 are basically consistent with the corresponding response of the step when the final roof is formed (construction step 43). This indicates that the non-bracket method in this paper could accurately control the prestress flow;
5. The results of the structure formed after construction (including structural deformation, structural stress, and cable force) are similar to the corresponding results of the dead load state, indicating that the construction method is feasible and has good accuracy.