Scaffolding is a working platform constructed to ensure the smooth progress of various construction processes. It is categorized by its location into outer scaffolding and inner scaffolding; by material into wooden scaffolding, bamboo scaffolding, and steel pipe scaffolding; and by construction form into upright scaffolding, bridge scaffolding, gate 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 coupling scaffolding, although some use door frame scaffolding. For main structure construction, the most common type of scaffolding used is the clip scaffolding. The longitudinal spacing of the scaffolding uprights is generally 1.2 to 1.8 meters; the transverse spacing is typically 0.9 to 1.5 meters.
Comparatively speaking, scaffolding has the following characteristics in working conditions 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. The scaffolding structure and components have initial defects, such as initial bending of the poles, rust, large installation size errors, and eccentric loading.
4. The connection points to the wall exhibit significant variation in their constraint on the 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 the fundamental condition for design calculations.
