Scaffolding is a working platform erected to ensure the smooth progress of each construction process. As an almost indispensable part of the construction project, its erection operation is crucial to the entire project.
First, the quality standards of scaffolding accessories
1. Steel pipe
(1) The steel pipe is a No. 3 steel welded steel pipe with an outer diameter of 48mm and a wall thickness of 3.5mm. It should have a product quality certificate and inspection report. Severely rusted steel pipes must be replaced and must not be used to erect the frame.
(2) The surface of the steel pipe should be straight and smooth, and there should be no cracks, scars, delamination, dislocation, hard bends, burrs, indentations, and deep scratches. Severely rusted, bent, flattened, damaged and cracked steel pipes must not be used.
(3) The steel pipe is painted with anti-rust paint. The vertical poles and horizontal poles are painted with yellow anti-rust paint, and the scissors braces and handrails are painted with red and white paint. The maximum weight of each steel pipe should not exceed 25 kg. Punching holes in the steel pipe is strictly prohibited.
(4) The length of the steel pipe for the vertical pole and the longitudinal horizontal pole (large crossbar) is 3-6 meters, the length of the steel pipe for the transverse horizontal pole (small crossbar) is 1.1~1.3 meters, and the length of the steel pipe for the transverse diagonal brace is 3-4 meters.
2. Fasteners
(1) New fasteners should have a production license, product quality certificate, and inspection report. Old fasteners should be inspected for quality before use. Those with cracks or deformation are strictly prohibited from use. Bolts with stripped threads must be replaced. Both new and old fasteners should be treated with rust prevention. Severely rusted fasteners and damaged fasteners should be repaired and replaced in time. Bolts should be oiled to ensure easy use.
(2) The contact surface between the fastener and the steel pipe should be good. When the fastener clamps the steel pipe, the minimum distance at the opening should be less than 5mm. The fasteners used must not be damaged when the bolt tightening force reaches 65N.m.
Second, the construction process, methods, and requirements of scaffolding erection
(First) Scaffolding frame form: This project adopts 16# I-beam cantilever single-pole double-row external scaffolding. The cantilever scaffolding has a step distance of 1.8m, a vertical distance of 1.5m, and a distance between the inner and outer rows of poles of 0.85m; the small crossbar is set below the large crossbar, the distance between the outer large crossbar is 0.9m, the distance between the inner large crossbar is 1.8m, and a horizontal crossbar is added in the middle of the small crossbar.
(Second) Scaffolding erection construction process
1. Scaffolding cantilever beam placement
(1) The cantilever beam lifting ring is embedded in advance according to the plan requirements, with accurate position and appropriate size.
(2) Layout and position according to the requirements of the vertical and horizontal distances of the scaffolding.
(3) Place the cantilever beam I-beams one by one. After the I-beams are placed and positioned, they are welded and anchored with steel bars.
(4) When lifting the cantilever beam, lift it gently to reduce the impact on the safety of the concrete structure.
2. The order of erecting scaffolding
Starting from one end of the corner of the building, erect the vertical poles one by one → place the longitudinal sweeping pole (the large horizontal pole close to the cantilever beam), and then fasten it with the vertical pole → install the transverse sweeping pole (the small horizontal pole close to the cantilever beam), and fasten it with the vertical pole → after erecting 3-4 vertical poles, install the first large horizontal pole (pay attention to fasten it with each vertical pole) → install the first small horizontal pole (fasten it with the large horizontal pole) → install the wall connection (or temporary support) → install the second large horizontal pole → install the second small horizontal pole → the third and fourth large horizontal poles and small horizontal poles → add wall connection poles at the corresponding positions → connect each vertical pole (all 6m in length) → add scissor braces and transverse diagonal braces → erect waist handrails and footboards → fully lay the bottom scaffolding boards → hang the safety net (including flat nets and vertical nets).
3. Precautions for scaffolding erection
(1) Before fixing the bottom end of the vertical pole, a line should be hung to ensure that the vertical pole is vertical.
(2) After correcting the verticality of the vertical poles and the horizontality of the large crossbars to meet the requirements, tighten the fastener bolts to form the starting section of the frame, and extend forward in sequence according to the above erection order until the first step of the frame is completed. After each step of scaffolding is erected, correct the step distance, longitudinal distance, transverse distance, and verticality of the vertical poles to ensure that they meet the requirements, set the wall connection parts, and erect the next step.
(3) The scaffolding must be erected by the construction progress, and the erection height at one time should not exceed two steps above the adjacent wall connection parts.
(Third) Scaffolding erection method and requirements
1. Requirements for sweeping rod erection: The longitudinal sweeping rod is fixed to the vertical pole at a distance of no more than 100mm from the base surface with a right-angle fastener. The transverse sweeping rod is fixed to the vertical pole close to the bottom of the longitudinal sweeping rod with a right-angle fastener.
2. Requirements for pole erection
(1) The steel pipes used for the vertical poles must be painted with anti-rust paint, and bent steel pipes must not be used. The vertical poles must be at least 1.5-1.8m higher than the working surface.
(2) Detailed procedures for pole joints: the poles must be extended by butt joints, the butt joint fasteners on the poles should be arranged in a staggered manner, the joints of two adjacent poles should not be set in the same span, the height offset distance of the joints of two adjacent poles should not be less than 500mm, and the distance between the center of each joint and the main node should not be greater than 1/3 of the step distance.
3. Requirements for the erection of large crossbars
(1) The large crossbar is set on the inside of the poles and fixed to the poles with right-angle fasteners. Its length should not be less than 3 spans. In the same step of the scaffolding, the large crossbar should be crossed all around and fixed to the inner and outer corner poles.
(2) Detailed procedures for large crossbar joints: the large crossbar should be butt jointed, the butt joints should be arranged in a staggered manner, and should not be set in the same span of the same synchronization. The horizontal distance between adjacent joints should not be less than 500mm, and the distance between the joint and the adjacent pole should not be greater than 1/3 of the pole spacing.
4. Requirements for the erection of small crossbars
A small crossbar must be set at the main node (the intersection of the vertical pole and the large crossbar) and fastened to the upper part of the large crossbar with a right-angle fastener. The outer end should extend for not less than 100mm, and the end against the wall should extend for not less than 200mm. The distance to the wall decoration surface should not be greater than 100mm. The distance of the axis of the rod from the main node should not be greater than 150mm.
5. Requirements for fastener installation
(1) The fastener specification must be the same as the outer diameter of the steel pipe.
(2) The tightening torque of the fastener should be 40-50N.m, and the maximum should not exceed 60N.m. It must be ensured that each fastener meets the requirements.
(3) The center points of the right-angle fasteners and rotating fasteners used to fix the small crossbar, large crossbar, scissor brace, horizontal diagonal brace, etc. at the main node should not be greater than 150mm.
(4) The opening of the butt fastener should face the inside of the scaffolding, and the opening of the right-angle fastener should not face downward.
(5) The length of each rod end extending out of the edge of the fastener cover plate should not be less than 100mm.
6. Requirements for the connection between the frame and the building structure
(1) Structural form: The connection point is fixed to the embedded steel pipe with a steel pipe fastener, and the cantilevered horizontal steel beam is connected to the building with a steel wire rope. The tie rod must be set on the vertical pole and pull the inner and outer vertical poles at the same time. The tie rod is arranged horizontally. When it cannot be arranged horizontally, the end connected to the scaffolding should be connected downward and not upward.
(2) Layout requirements: The wall connection is arranged in two steps and three spans, with a vertical spacing of 3.6m and a horizontal spacing of 4.5m. Double fasteners are used for connection. The scaffolding must be firmly connected to the main body of the building. When setting, it should be as close to the main node as possible, and the distance from the main node should not be greater than 300mm. It must be set from the first large horizontal bar at the bottom and arranged in a diamond shape.
(3) The fasteners used at the connection point must meet the requirements, and there must be no loose fasteners or bending of embedded steel pipes.
7. Method of erecting scissor braces
(1) Scissor braces are continuously installed along the entire length and height of the outside of the scaffolding. Each scissor brace connects 5 vertical poles. The scissor braces should be erected synchronously with the vertical poles, large horizontal poles, small horizontal poles, etc.
(2) The diagonal rod of the scissor brace is fixed to the protruding end of the large horizontal pole or the vertical pole with a rotating fastener. The distance between the center line of the rotating fastener and the main node should not be greater than 150mm. In addition to fastening the diagonal rod with the vertical pole at both ends, 2-4 fastening points should be added in the middle. The distance between the end of the lowest diagonal rod and the vertical pole should not be greater than 500mm. The inclination angle between the diagonal rod and the ground should be between 45° and 60°.
(3) The extension of the scissor brace is overlapped, and the overlap length is not less than 1 meter. Three fasteners are arranged at equal distances, and the fasteners are fastened less than 100mm from the end of the steel pipe.
8. Laying of scaffolding boards
(1) Scaffolding boards should be placed on three small crossbars and should be fully, tightly, and firmly laid, 300mm away from the wall.
(2) Laying method: Scaffolding boards should be laid flat, and two small crossbars must be set under the joints of scaffolding boards laid end to end. The extended length of the scaffolding boards should be 130~150mm, and the sum of the extended lengths of the two scaffolding boards should not be greater than 300mm; when scaffolding boards are laid in overlapping positions, the joints must be supported on small crossbars, the overlapping length should be greater than 200mm, and the length extending from the small crossbar should not be less than 100mm. Scaffolding boards at corners must be laid crosswise. The scaffolding board probes are fixed to the large crossbars with 18# iron wire. Scaffolding boards at corners and ramp platform entrances should be reliably connected to the small crossbars to prevent sliding.
(3) The construction layer must be fully covered with scaffolding boards.
9. Internal enclosure and external protection of scaffolding
(1) Guardrails 900mm high must be installed on the outside of each step of the scaffolding.
(2) On the inside of the external uprights of the scaffolding, a dense safety net must be installed horizontally from bottom to top.
(3) The external scaffolding must be enclosed every three floors on the cantilevered floors. This project uses wooden formwork for enclosing.
(Fourth) Quality requirements for scaffolding erection
1. Verticality deviation of uprights: The verticality deviation of uprights should not exceed H/300, and at the same time, its absolute deviation value should not exceed 75mm. The height deviation should not exceed H/300, and should not exceed 100mm.
2. Horizontal deviation of large crossbars: The height difference between the two ends of a large crossbar should not exceed 20mm, the horizontal deviation of the large crossbar should not exceed 1/300 of the total length, and the flatness deviation of the entire length should not exceed ±100mm. The height difference between two large horizontal bars in the same span shall not exceed 10mm;
3. The horizontal deviation of the small horizontal bar shall not exceed 10mm, and the deviation of the extension length shall not exceed -10 mm.
4. The deviation of the scaffolding step and the horizontal distance of the vertical pole shall not exceed 20mm, and the vertical distance of the vertical pole shall not exceed 50mm.
5. The number and position of the wall connecting parts shall be correct, the connection shall be firm, and there shall be no looseness.
6. The safety net must use qualified products and be tied firmly. There shall be no damage or incomplete binding.
7. The steel fence must be tied firmly with 18# iron wire. Looseness and probe plates are strictly prohibited.
8. The I-beams and wire ropes used for cantilevering must meet the requirements of the briefing, and other unqualified materials shall not be used in violation of regulations.
Third, safety technical measures for scaffolding erection and use
1. Scaffolding erection personnel must be professional scaffolding workers who have passed the assessment. On-the-job personnel should undergo regular physical examinations, and only those who pass the examination can be certified to work.
2. Personnel setting up scaffolds must wear safety helmets correctly, fasten safety belts, and wear non-slip shoes. When setting up scaffolds, fences and warning signs should be set up on the ground, and special personnel should be assigned to guard. Non-operating personnel are strictly prohibited from entering.
3. The quality of the components and the quality of the scaffolding should be inspected and accepted, and they can only be used after passing the inspection.
4. During the use of scaffolding, the following items should be checked regularly:
① Whether the setting and connection of rods, the construction of wall connecting parts, supports, door opening trusses, etc. meet the requirements;
② Whether there is water accumulation in the foundation, whether the base is loose, and whether the vertical pole is suspended;
③ Whether the fastener bolts are loose;
④ Whether the settlement and vertical deviation of the vertical pole meet the regulations;
⑤ Whether the safety protection measures meet the requirements;
⑥ Whether it is overloaded.
5. During the use of scaffolding, it is strictly forbidden to remove the following rods: ① Large crossbars, small crossbars, longitudinal and transverse sweeping rods at the main nodes; ② Wall connecting parts.
6. When workers are working on the frame, they should pay attention to their safety and protect the safety of others, avoid collisions, accidents, and falling objects; it is strictly forbidden to play on the frame and sit on the railings and other unsafe places to rest.
7. It is strictly forbidden to stack wood, steel pipes, fasteners, top supports, steel bars, and other construction materials on the cantilever frame.
8. It is strictly forbidden for any team to connect the external frame with the full-floor frame.
9. When the external frame is erected, it must be ensured that the connection is firm at one time. If it is necessary to stop work in heavy rain and wind, the stability of the frame must be ensured.
10. Work must be stopped in heavy rain, wind, and thunderstorms, and no risky construction is allowed.
11. If the suspension time is long, when the external frame is used again, it must be inspected and accepted again before it can be used.
12. The erection of the external frame must be implemented according to the plan.
Supplementary content:
a) The erection requirements of the internal frame such as the elevator shaft are the same as the external frame. The steel beams and closure requirements of the cantilever position are to the requirements of the external frame.
b) The inner frame must be fully covered with steel fences below the operating floor, and the frame must be fixed on the wall with short steel pipes or top supports.
c) The cantilevered horizontal steel beam uses 16# I-beam, of which the cantilever section outside the building is 1.4m long and the anchor section inside the building is 2.1m long. The diameter of the anchoring pressure ring steel bar is 20mm.
d) The upper lifting ring uses Ω-shaped Φ20 steel bars embedded in the beam.
Post time: Jun-19-2025