What preparations should be made before dismantling scaffolding?

(1) Whether the fastener connection, wall parts and support system of scaffolding meet the structural requirements should be comprehensively checked.

(2) The demolition sequence and measures in the complete construction organization design should be supplemented according to the inspection situation, and can be implemented only after being approved by the competent department.

(3) Demolition safety technical disclosure shall be carried out by the project leader of this unit.

(4) Debris and ground obstacles on scaffolding should be removed.

Frequently asked questions:

1, design

(1) Have a clear understanding of heavy scaffolding. Generally, if the floor thickness exceeds 300mm, it is necessary to consider the design of heavy scaffolding. If the scaffold load exceeds 15KN/_, experts shall be organized to demonstrate the design scheme. In order to distinguish the parts where the change of steel pipe length has great influence on the bearing capacity, formwork support should consider:

The center line of the top horizontal bar should not be too long from the support point of the formwork, and generally it should be less than 400mm (it may be modified in the new specification). When calculating the vertical pole, the top step and the bottom step are generally the most stressed as the main calculation points. When the bearing capacity does not meet the requirements of the group, vertical poles should be added to reduce the vertical and horizontal spacing, or horizontal poles should be added to reduce the step distance.

(2) The quality of steel pipes, fasteners, top bracing, bottom bracing and other materials of domestic scaffolding is generally unqualified, which is not considered in theoretical calculation in actual construction. It is best to take a certain safety factor in the design and calculation process.

2. Architecture

The sweeping bar is missing, the vertical and horizontal junctions are not connected, and the distance between the sweeping bar and the ground is too large or too small; The scaffold board is cracked, the thickness is not enough, and the lap joint does not meet the specification requirements; After the large formwork is removed, there is no anti-falling net between the inner column and the wall.

The support is discontinuous in the plane; The open scaffold is not provided with diagonal braces; The small bar spacing under the scaffold is too large; Even the wall part has no rigid connection between inside and outside; The distance between protective railings is greater than 600mm；; Fastener connection is not tight, fastener slippage, etc.

3. Deformation accident

(1) Local deformation of scaffold caused by foundation settlement. On the cross section of the double bent frame, a figure of eight or bracing is arranged, and a group of vertical rods are arranged every other row until the deformation zone is discharged. Eight-legged or scissors waste must be placed on a solid and reliable foundation.

(2) If the deflection of the cantilever steel beam rooted by the scaffold exceeds the specified value, the rear anchorage point of the cantilever steel beam should be reinforced, and the steel support and U-shaped bracket should be used to tighten the steel beam to make it stand against the roof. There is a gap between the embedded reinforcing ring and the steel beam, which must be tightened with a horse wedge. Check the wire ropes hanging at the outer ends of steel beams one by one, and tighten them all to ensure uniform stress.

(3) If the scaffold unloading system is damaged locally, it shall be repaired immediately according to the unloading method formulated in the original scheme, and the deformed parts and bars shall be corrected.

For correcting the outward deformation of scaffolding, first set a 5t chain block for each bay, tighten it with the structure, loosen the rigid pull contact, and at the same time tighten the chain block inward at each point until the deformation is corrected, and do a good job in rigid pull connection, tighten the steel wire rope at each unloading point to make it uniformly stressed, and finally release the chain block.