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, bridge, door, suspended, hanging, cantilever, and climbing scaffolding.
Different types of construction projects require different types of scaffolding. Most bridge support scaffolding uses bowl coupling scaffolding, but some also use portal scaffolding. The most common type of scaffolding used for the main structure construction is the clamp-type scaffolding, with the longitudinal spacing of the scaffolding posts typically 1.2~1.8m and the transverse spacing generally 0.9~1.5m.
Comparatively speaking, scaffolding has the following characteristics in terms of working conditions compared to general structures:
1. The load variability is 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 assembly size errors, and eccentric loading, all of which are considerable.
4. The connection points to the wall exhibit significant variation in their constraint on the scaffolding. Research on the above issues lacks systematic accumulation and statistical data, and 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 it against previously used coefficients. 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.
