## 3 Non-Bracket Construction Method  
The construction of a cable strut tension structure is a dynamic process that involves gradually integrating basic components into a partial structure and then the complete structure. In this process, the shape, stiffness, boundary, and load conditions are constantly changing, and the transformation from mechanism to structure is realized according to a certain topological relationship. For a spatial structure with such characteristics, the non-bracket construction method can realize a natural integral transition of the cable net from the non-stress state mechanism to the designed stress level state structure and ensure the gradual development of the structure configuration and stiffness in the whole process of construction. However, some new difficulties will be encountered in the construction of an annular cable supported grid structure when the brackets are canceled. The core problem is that the cable net and grid configuration will be out of control due to a temporary formation failure of the self-balancing system of the structure during the construction process. With the non-bracket construction method proposed in this paper, the accuracy of the cable net configuration and the grid installation position can be controlled by tensioning the tie-downs at the tension ring nodes (i.e., the cable clamps) when the self-balancing system is not fully formed. Compared with the traditional construction method, the non-bracket construction method has the following advantages:  
1. For the cable supported grid structure with external CR, the upper grids basically do not participate in the balance of pre-tension; the pre-tension should be balanced by the CR. The traditional method of first completing the upper grid and then installing and tensioning the cable net will result in the installed upper grids participating in the balance of pre-tension of cable force during the construction process, which will lead to differences in pre-stress distribution between the final formed state and the designed equilibrium state. The non-bracket construction method divides the entire  
Figure 4: Layout of cable net. structure into a tension substructure and post-installed components (Figure 5). The tensioning substructure is completed first to establish the pre-stress distribution to meet the design expectation without interference from other components. After that, the incomplete structure is maintained at the design equilibrium position by adjusting the cable forces of tie-downs during the subsequent installation of components such as the upper grid. This means that the pre-stress flow is distributed in the designed pre-stress components during the entire construction process, and the non-bracket method can ensure a more accurate pre-stress distribution especially in the cable supported grid structures with CR. 2. Tie-downs can realize bidirectional, real-time and accurate adjustment of the elevation of the control nodes in the construction process and the erection of brackets is unnecessary, which means that it has fewer requirements for the construction site and is conducive to a flexible arrangement of the construction period for the grandstand and other structures. At the same time, due to the relatively simple construction equipment and fewer temporary construction facilities, this method is also economical.