Key Technical Points for the Construction and Installation of Cantilever Scaffolding

                                                            I. Technical Specifications:
Technical specifications for structures with a height not exceeding 30 meters

 

 

                                                                                      II. Construction Methods:
(1) Process Flow:
1. Installation of cantilever scaffolding: Horizontal cantilever → Longitudinal base rails → Uprights → Transverse base rails → Small crossbars → Large crossbars (decking) → Diagonal braces → Wall ties → Laying scaffold planks → Installing guardrails → Installing safety nets.
2. Dismantling of Cantilever Scaffolding: Follow the reverse order of the installation process (i.e., dismantle the sections installed first last, and the sections installed last first).
3. Wire Rope Unloading: Arrange lifting points → Select specifications according to design requirements → Set up wire rope unloading points in accordance with the design. 

 

(II) Construction Methods
1. Horizontal Cantilever Beams:
① For horizontal cantilever beams, the horizontal spacing between I-beams shall be 1,500 mm, and the cantilever length shall be 1,200 mm. The length of the fixed section shall not be less than 1.25 times the length of the cantilever section. When anchor points are located on the floor slab, the slab thickness shall not be less than 120 mm. Reinforcing bars designed to resist the negative bending moments caused by the anchoring end of the cantilever beam shall be pre-installed in the floor slab; otherwise, shoring measures shall be taken to relieve the load.
② Where cantilevered I-beams intersect at structural outside corners and the projection length cannot be guaranteed, the I-beams on both sides shall be welded to the I-beam at the outside corner at the intersection point, with an additional
-200×200×10 mm steel plate added above and below. All contact points must be fully welded; the weld bead height shall not be less than 8 mm, and there shall be no porosity, slag inclusions, or missed welds, as shown in the figure below:

 

 

2. Anchoring of Cantilever Beams:
The trailing end of a cantilever beam shall be secured to the reinforced concrete beam-and-slab structure at two or more points. The fixed ends of steel cantilever beams shall be secured by welding 20 mm diameter HPB300-grade round steel compression rods to anchor rings. The round steel anchor rings shall be embedded to the level of the bottom reinforcement of the concrete beams and slabs and shall be securely anchored by welding or tying to the bottom reinforcement of the concrete beams and slabs. If the cantilever beam passes through a wall, it shall be secured with wooden wedges. As shown in the figure below:

 

 

 

(3) Wire Ropes:
1. Wire ropes on cantilevered I-beams: All I-beams are equipped with 2 strands of Φ15.5 (6×19) or 2–3 strands of Φ17 (6×19) wire ropes, which are not included in structural load calculations and serve solely as safety measures; refer to the wire rope layout plan for details. The lifting rings connecting the steel wire ropes to the building structure shall be made of HPB300-grade round reinforcing bars with a diameter of 20 mm. No more than two steel wire ropes shall be attached to each anchor ring; if more are required, separate anchor rings shall be provided. At the lower end of the connection between the I-beams and the steel wire ropes, a reinforcing bar with a diameter of 16 shall be welded in place as an anti-slip component to prevent the steel wire ropes from slipping. The detailed drawing is shown below:

 

 

 

(5) Installation of Main Horizontal Beams and Secondary Horizontal Beams:

1. Main horizontal beams are positioned inside the vertical posts, with an overhang of approximately 100 mm on each side.

2. On the outer scaffolding, secondary horizontal beams are installed at the intersections of the vertical posts and main horizontal beams, with both ends secured to the vertical posts to ensure the spatial structure bears loads as a whole. To facilitate the installation of steel mesh scaffolding planks, a filler bar is added to the secondary horizontal beams.

3. Where the inner row of a local external scaffold is located far from the building, the small crossbars may be extended or an additional small crossbar may be added, provided that the overhang does not exceed 0.4 times the calculated length of the small crossbar.

(6) Requirements for Laying Steel Mesh Panels:

1. Steel mesh panels must be laid completely and fully in place, leaving no gaps; effective protective measures must be taken where full coverage is not possible.

2. Steel mesh panels must be tied using double strands of No. 12–14 lead wire in parallel, with no fewer than 4 tie points. The ties must be secure, and the joints must be smooth. Only undamaged steel mesh panels should be used during installation; any damaged panels must be replaced immediately.

3. The dead weight of the steel mesh panels shall not exceed 0.1 kN/m², and the dead weight of the toe boards shall not exceed 0.01 kN/m².