Scaffolding is a working platform constructed to ensure the smooth progress of various construction processes. It is categorized by its placement into external and internal scaffolding; by material into wooden, bamboo, and steel pipe scaffolding; and by construction form into upright, bridge, gate, suspended, hanging, cantilever, and climbing scaffolding.
Different types of construction projects require different types of scaffolding. Bridge supports predominantly use bowl clamp scaffolding, with some using gate scaffolding as well. For main structure construction, most use clamping scaffolding for ground-level scaffolding. The longitudinal distance of the scaffolding uprights is generally 1.2~1.8m, and the transverse distance is generally 0.9~1.5m.
Comparatively, scaffolding has the following characteristics in working conditions compared to general structures:
1. The load variability is significant.
2. The connecting 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, rusting, significant setup size errors, and eccentric loading, all of which are considerable.
4. The connection points with the wall exhibit significant variability in their constraint on the scaffolding. There is a lack of systematic accumulation and statistical data regarding the above issues, and the conditions for conducting independent probability analysis are not met. Therefore, the value of the adjustment coefficient, which is multiplied by the structural resistance and is less than 1, is determined by calibrating it against the coefficients used in the past. Consequently, the design method adopted in this specification is essentially a hybrid of semi-probabilistic and semi-empirical. Compliance with the structural requirements specified in this specification is the fundamental condition for design calculations.
