3.1.1. Geometric Dimension

The elevation of the dome reaches 39.7 m, the span of the square loop-string structure is 106.5 m, the span of the main truss of grid beams peaks at 97.5 m with the distance between main trusses ranging from 6.3 m to 7.6 m and the distance between secondary trusses is 9.5 m. The four sides of the dome have a relatively large load area with longspan horizontal cables. To increase the vertical rigidity of the structure, two middle struts (SC13~SC16) are added on the north and south sides of the outer square ring cables and independent string beams (SH13~SH14) are erected both on the east and west sides, the maximum span of which is 75.9 m. The struts and cables of the MSL-S structure system are shown in Figure 2.

**Figure 2.** Schematic diagram for the number of struts and cables. (**a**) Strut numbers; (**b**) Number of square ring cables and stay cables.
