Scaffolding is a working platform constructed to ensure the smooth progress of various construction processes. It is categorized by its placement into outer scaffolding and inner scaffolding; by material into wooden scaffolding, bamboo scaffolding, and steel pipe scaffolding; and by construction into upright scaffolding, bridge scaffolding, door scaffolding, suspended scaffolding, hanging scaffolding, cantilever scaffolding, and climbing scaffolding.
Different types of construction projects require different types of scaffolding. Most bridge supports use bowl clamp scaffolding, with some using gate scaffolding. For the main structure construction, most use clamp scaffolding for ground-level scaffolding. The longitudinal spacing of the scaffolding uprights is generally 1.2~1.8m; the transverse spacing is generally 0.9~1.5m.
Comparatively, scaffolding has the following characteristics in working conditions when compared to general structures:
1. The load variability is quite significant.
2. The connection nodes of fasteners are semi-rigid, and the rigidity of the nodes is related to the quality of the fasteners and the installation quality, with significant variation in node performance.
3. Scaffold structures and components have initial defects, such as initial bending of rods, rust, significant installation size errors, and eccentric loading, all of which are considerable.
4. The connection points with the wall exhibit significant variability in their constraint to the scaffolding. There is a lack of systematic accumulation and statistical data on the above issues, which does not meet the conditions for conducting independent probability analysis. Therefore, the adjustment coefficient less than 1 for the structural resistance is determined by calibrating with the coefficients used in the past. Consequently, the design method adopted in this specification is essentially semi-probabilistic and semi-empirical. Compliance with the structural requirements specified in this specification is the fundamental condition for design calculations.
