Scaffolding is a working platform constructed to ensure the smooth progress of various construction processes. It is categorized by installation location into external and internal scaffolding; by material into wooden, bamboo, and steel pipe scaffolding; and by construction form into vertical pole, bridge, gate, suspended, hanging, cantilever, and climbing scaffolding.
Different types of construction projects require different types of scaffolding. Most bridge support scaffolding uses bowl clamp scaffolding, but some also use portal scaffolding. The majority of ground scaffolding for main structure construction uses clamp scaffolding, with the longitudinal spacing of scaffold posts generally being 1.2 to 1.8m; the transverse spacing is generally 0.9 to 1.5m.
Scaffolding, compared to general structures, has the following characteristics in terms of working conditions:
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, with significant variation in node performance.
3. Scaffold structures and components have initial defects, such as initial bending of rods, rusting, significant setup dimension 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 for the study of the above issues, thus not meeting the conditions for independent probability analysis. Therefore, the value of the adjustment coefficient, which is multiplied by the structural resistance and is less than 1, is determined by calibrating against coefficients used in the past. Consequently, the design method adopted in this specification is essentially a combination of semi-probabilistic and semi-empirical approaches. Compliance with the structural requirements specified in this specification is a fundamental condition for design calculations.
