3.1.2. Design Scheme of Loading Device with a Single Set of Pulley Group

Following the design principle discussed in the previous section, the design of the single-pulley-group loading device was completed, as shown in Figure 7. In this apparatus, the movable pulley group is connected to the main arch ring through the main arch ring's fixture and connecting rod. The stationary pulley group is connected to the ground using the lower jig and the lower jig base. Both pulley groups consist of three steel pulleys, with diameters of 310 mm, 230 mm, and 130 mm, respectively. The steel wire rope has a diameter of 8.7 mm. A counterweight box is used to house the counterweights, allowing sequential loading based on experimental requirements. The tension sensor can display and record the load values at the loading points on the main arch ring in real time.

**Figure 7.** Schematic diagrams of a single-pulley-group loading system. (**a**) Overall diagram of a loading system with a single set of pulley group; (**b**) Partial view of a loading system with a single set of pulley group.
