Due to high clearances and large spans, some areas of reinforced concrete buildings, such as the entrance lobby of a hospital or the stage area of an auditorium, often need to design large-scale isolated reinforced concrete beams to support the weights from slabs and beams. On construction sites, the falsework of single-line steel scaffolds is often set up underneath these isolated beams based on the lined setup. Since the setup of these steel scaffolds is unique and data available for designing are lacking, single-line steel scaffolds are often installed on construction sites based on workers’ experience. Study results show that the load capacities of one-bay, two-story door-type steel scaffolds (2D) are similar to those of one-bay, three-story door-type steel scaffolds (3D). When adopting multi-bay setups, the load capacities of two-story door-type steel scaffolds (2D) and of one-door, one-square, two-rectangle steel scaffolds (DS2R) increase with the number of bays. Although the height of the DS2R setup is higher than that of the 2D setup, the load capacity of the DS2R setup is still higher than that of the 2D setup, indicating that the strength of the combined setup of steel scaffolds is higher than that of pure door-type steel scaffolds. By applying the second loading using reusable materials, to simulate the load capacity of the steel scaffolds under the worst conditions, this study obtained the strength reduction factors of the steel scaffolds using reusable materials.