Scaffolding is a working platform designed to ensure the smooth progress of various construction processes. It is categorized by installation location into outer scaffolding and inner 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 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 scaffold posts is generally 1.2~1.8m; the transverse spacing is generally 0.9~1.5m.
Comparatively speaking, 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 the 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, rust, significant dimensional errors in assembly, and eccentric loading, all of which are considerable.
4. The connection points to the wall exhibit significant variation in their restrictive nature for 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 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.
