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 form into upright post scaffolding, bridge scaffolding, portal scaffolding, suspended scaffolding, hanging scaffolding, cantilever scaffolding, and climbing scaffolding.
Different types of construction projects require different types of scaffolding. Most bridge support structures use bowl clamp scaffolding, with some using gate scaffolding. For the construction of the main structure, most use clamp scaffolding for ground-level scaffolding; the longitudinal spacing of the scaffolding posts is generally 1.2~1.8m; the transverse spacing is generally 0.9~1.5m.
Scaffolding, compared to general structures, has the following characteristics in terms of working conditions:
1. The load variability is quite significant.
2. The connecting 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, corrosion, large installation size errors, and eccentric loading.
4. The connection points to the wall exhibit significant variability in their constraint on scaffolding. There is a lack of systematic accumulation and statistical data regarding the above issues, which does not meet 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 semi-probabilistic and semi-empirical approach. Compliance with the structural requirements specified in this specification is a fundamental condition for design calculations.
