Characteristics of Scaffolding
Different types of scaffoldings are selected for different purposes of engineering construction. Most of the bridge support frames use bowl-buckled scaffolding, and some use portal scaffolding. In the construction of main structure, fastener scaffolding is mostly used. The longitudinal distance of scaffolding poles is generally 1.2 to 1.8 m, and the transverse distance is generally 0.9 to 1.5 M.
Compared with the general structure, the working conditions of scaffolding have the following characteristics:
1. Load variability is large.
2. Fastener connections are semi-rigid, and the stiffness of the joints is related to the quality of fasteners and installation quality, and the performance of the joints varies greatly.
3. There are initial defects in scaffolding structure and components, such as initial bending and corrosion of members, erection size error and load eccentricity.
4. The constraints on scaffolding vary greatly at the joints with walls. The research on the above problems lacks systematic accumulation and statistical data, and does not have the condition of independent probability analysis. So the value of the adjustment coefficient multiplied by the structural resistance less than 1 is correctly calibrated with the safety factor used in the past. Therefore, the design method adopted in this code is semi-probabilistic and semi-empirical in essence. The basic condition of design and calculation is that scaffolding meets the construction requirements specified in this code.