3.1.3. Finite Element Model Creation

General finite element software SAP2000 V19 was used to establish the three-dimensional finite element model of the string dome structure of the gymnasium. The roof grid beams used the steel box-sections simulated by the Frame unit, the prestressed cables were simulated by the Cable unit and the struts were simulated by the Link unit. The struts nodes at both ends were simulated as articulated to ensure the smooth rotation during the prestressing process. The berm under the roof, an auxiliary structure of grid structure system, was applied to the corresponding struts in the form of a line load (1.5 kN/m) after simplification; Given the additional load of the cable connection device, PE pipes and fillers, the weight of the cables was multiplied by a coefficient of 1.05. With the ring beams outside the grid beams connected with the concrete column nodes, the degrees of freedom in six directions were coupled, and the bottom of concrete column was a fixed end constraint. The three-dimensional finite element model is shown in Figure 1a.
