Scaffolding is a working platform erected to ensure the smooth progress of various construction processes. As an almost indispensable part of construction projects, its erection operations are crucial to the entire project.
First, quality standards for scaffolding structure accessories
1. Steel pipe
(1) The steel pipe is made of 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 ones must be replaced and must not be used to erect the frame.
(2) The surface of the steel pipe should be straight and smooth, without cracks, scabs, delaminations, misalignments, hard bends, burrs, indentations, and deep scratches. There should be no serious corrosion, bending, flattening, damage, or cracks. use.
(3) The steel pipe is coated with anti-rust paint. The vertical poles and horizontal poles are painted with yellow anti-rust paint, and the scissor supports and handrail tubes are painted with red and white paint. The maximum mass of each steel pipe should not be greater than 25 kg. It is strictly prohibited to drill holes in steel pipes.
(4) The length of steel pipes for vertical poles and longitudinal horizontal poles (large horizontal poles) is 3-6 meters, the length of steel pipes for horizontal poles (small horizontal poles) is 1.1-1.3 meters, and the length of transverse diagonal brace steel pipes 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 deformations are strictly prohibited from use. Bolts with slippage must be replaced. Both new and old fasteners should be treated with rust prevention. Repair severely corroded fasteners and damaged fasteners and replace bolts in time. Oiling the bolts ensures ease of use.
(2) The fitting surface of the fastener and the steel pipe should be in good contact. When the fastener clamps the steel pipe, the minimum distance between the openings should be less than 5mm. The fasteners used must not be damaged when the bolt tightening force reaches 65N.m.
Second, the construction procedures, methods, and requirements of scaffolding
(1) Scaffolding form
This project uses 16# I-beam cantilevered single pole and double-row exterior scaffolding. The step distance of the cantilever scaffolding is 1.8m, the vertical distance of the poles is 1.5m, and the distance between the inner and outer rows of poles is 0.85m; the small crossbars are set below the large crossbars, the distance between the outer large crossbars is 0.9m, and the distance between the inner large crossbars is 1.8m. A horizontal crossbar is added to the middle of the small crossbar.
(2) Scaffolding erection and construction process
1. Placement of shelf cantilever beams
(1) The hanging beam lifting rings are pre-embedded according to the plan requirements, with accurate position and appropriate size.
(2) Set out and position according to the vertical and horizontal distance requirements of the scaffolding.
(3) Place the I-beams of the cantilever beams one by one. After the I-beams are placed, the wires are drawn and positioned, and then welded and anchored with steel bars.
(4) When lifting the beam, lift it gently to reduce the impact on the safety of the concrete structure deflection.
2. Scaffolding erection sequence
Set up vertical poles one by one starting from one end of the corner of the building → place the vertical sweeping pole (large horizontal pole close to the cantilever beam), and then fasten it to the vertical pole → install the horizontal sweeping pole (small horizontal pole close to the cantilever beam), and Fasten with the vertical poles → After erecting 3-4 vertical poles, install the large horizontal bars in the first step (pay attention to fastening with each vertical pole) → Install the small horizontal bars in the first step (fasten with the large horizontal bars) → Install the connecting Wall fittings (or temporary throw supports) → Install the large crossbar in the second step → Install the small crossbar in the second step → Large and small crossbars in the third and fourth steps → Add connecting wall rods at the corresponding positions → Connect each vertical Rods (both 6m in length) → Add scissor braces and transverse diagonal braces → Set up waist handrails and foot guards → Cover the bottom floor with scaffolding boards → Hang safety nets (including flat nets and vertical nets).
3. Things to note when erecting scaffolding
(1) Before fixing the bottom end of the pole, hang a wire to ensure that the pole is vertical.
(2) After correcting the verticality of the vertical pole and the horizontality of the large horizontal pole to meet the requirements, tighten the fastener bolts to form the starting section of the frame, and extend it forward in sequence according to the above erection sequence until the first step of the frame intersection is completed. After each step of scaffolding is erected, correct the step distance, vertical distance, horizontal distance, and verticality of the poles to ensure that they meet the requirements, then set up the wall fittings and erect the previous step.
(3) Scaffolding must be erected by the construction progress, and the height of a single erection should not exceed two steps above the adjacent wall parts.
(3) Scaffolding erection methods and requirements
1. Requirements for erecting the sweeping pole: The longitudinal sweeping pole is fixed on the vertical pole no more than 100mm away from the base epithelium using right-angle fasteners. The horizontal sweeping rod is fixed to the vertical pole immediately below the longitudinal sweeping rod using right-angle fasteners.
2. Pole erection requirements:
(1) The steel pipes used for poles must be coated with anti-rust paint, and bent steel pipes are not allowed. The vertical pole should be at least 1.5-1.8m higher than the working surface.
(2) Detailed methods of vertical pole joints: vertical poles must be lengthened by butt joints. The butt fasteners on the vertical poles should be arranged in a staggered manner. The joints of two adjacent vertical poles should not be set in synchronization. The staggered distance in the height direction of the joints 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. Large crossbar erection requirements:
(1) The large crossbar is set inside the vertical pole and fixed on the vertical pole with right-angle fasteners. Its length should not be less than 3 spans. In the same step of scaffolding, the large horizontal bars should be circled all around and fixed with the inner and outer corner poles.
(2) Detailed methods for large cross-bar joints: Large cross-bars should be jointed by butt joints. Butt joints should be arranged in a staggered manner and should not be located in the same span. The horizontal distance between adjacent joints should not be less than 500mm. The joints should be connected to adjacent vertical poles. The distance should not be greater than 1/3 of the pole spacing.
4. Requirements for erecting small crossbars:
A small horizontal bar must be installed at the main node (the intersection of the vertical pole and the large horizontal bar) and fastened to the upper part of the large horizontal bar using right-angle fasteners. The protruding length of the outer end shall not be less than 100mm, and the protruding length of the end against the wall shall not be less than 100mm. Less than 200mm, the distance to the wall decorative surface should not be greater than 100mm. The distance between the axis of the rod and the main node should not be greater than 150mm.
5. Fastener installation requirements:
(1) Fastener specifications must be the same as the outer diameter of the steel pipe.
(2) The tightening torque of fasteners 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 mutual distance between the center points of right-angle fasteners and rotating fasteners used to fix small crossbars, large crossbars, scissor braces, transverse diagonal braces, etc. at the main node should not be greater than 150mm.
(4) The opening of the butt fastener should face the inside of the shelf, and the opening of the right-angle fastener should not face downward.
(5) The length of each rod end protruding from the edge of the fastener cover shall not be less than 100mm.
6. Requirements for the tie between frame and building structure
(1) Structure form: The tie points are fixed on the embedded steel pipes with steel pipe fasteners, and the cantilevered horizontal steel beams are tied to the building using steel wire ropes. The tie rod must be set on the vertical pole and pull the inner and outer vertical poles at the same time. The tie rods are arranged horizontally. When they cannot be arranged horizontally, the end connected to the scaffolding should be connected at a downward slope and not upward.
(2) Arrangement requirements: The wall-connecting parts are arranged in two steps and three spans, with a vertical spacing of 3.6m and a horizontal spacing of 4.5m, and double fasteners are used for connection. The scaffolding must be firmly connected to the main body of the building. When setting, try to 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 up from the first large crossbar at the bottom in a diamond-shaped arrangement.
(3) The fasteners used at the tie points must meet the requirements, and there must be no loose fasteners or bending of the embedded steel pipe.
7. How to set up scissor braces
(1) Set scissor braces continuously along the entire length and height of the outside of the scaffolding. Each scissor brace is connected to 5 vertical poles. Scissor braces should be erected simultaneously with vertical poles, large horizontal poles, small horizontal poles, etc.
(2) The scissor brace diagonal bar is fixed on the extended end or vertical pole of the large horizontal bar that intersects with it 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 two ends of the inclined rod to the vertical pole, 2-4 buckling points should be added in the middle. The contact distance between the bottom end of the inclined rod and the vertical pole shall not be greater than 500mm. The inclination angle between the inclined pole and the ground should be between 45°-60°.
(3) The length of the scissor support shall be overlapped, and the overlap length shall not be less than 1 meter. Three fasteners shall be arranged equidistantly, and the fasteners shall be buckled at the end of the steel pipe less than 100 mm.
8. Laying of scaffolding boards
(1) The scaffolding boards should be set on three small crossbars, which should be fully, tightly, and steadily spread, 300mm away from the wall.
(2) Laying method: The scaffolding boards should be laid flat. Two small crossbars must be set under the joints of the scaffolding boards laid opposite to each other. The extension length of the scaffolding boards is 130~150mm. The sum of the extension lengths of the two scaffolding boards should not be greater than 300mm; when the scaffolding boards are overlapped and laid, the joints must be supported on the small crossbar, the overlap length should be greater than 200mm, and the length extending out of the small crossbar should not be less than 100mm. Scaffolding boards at corners must be laid crosswise. The scaffolding probe is fixed on the large crossbar with 18# iron wire. Scaffolding boards at corners and ramp platform openings should be reliably connected to small crossbars to prevent sliding.
(3) The construction layer must be covered with scaffolding boards.
9. Internal closure and external protection of scaffolding frame
(1) A protective railing 900mm high must be installed on the outside of each step of the scaffolding.
(2) A dense-mesh safety net must be installed horizontally and continuously from bottom to top on the inside of the outer pole of the scaffold.
(3) The external scaffolding must be closed every three floors on the cantilevered floors. This project uses wooden formwork for closure.
(4) Quality requirements for scaffolding erection
1. Pole verticality deviation: The verticality deviation of the pole should not be greater than H/300, and at the same time, the absolute deviation value should not be greater than 75mm. The height deviation shall not be greater than H/300 and shall not be greater than 100mm.
2. Horizontal deviation of large crossbars: The height difference between the two ends of a large crossbar cannot exceed 20mm. The horizontal deviation of large crossbars should not be greater than 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 of the same span shall not be greater than 10mm;
3. The horizontal deviation of the small crossbar shall not be greater than 10 mm, and the deviation of the extension length shall not be greater than -10 mm.
4. The deviation of the scaffolding step distance and the horizontal distance of the poles shall not be greater than 20mm, and the deviation of the vertical distance of the poles shall not be greater than 50mm.
5. The number and position of wall-connecting parts must be correct, the connection must be firm, and there must be no looseness.
6. The safety net must use qualified products and be tied firmly. There must be no damage or incomplete binding.
7. The steel fence pieces must be tied firmly with 18# iron wire, and loosening, probe boards, etc. are strictly prohibited.
8. The I-beams and steel wire ropes used in the cantilever must meet the disclosure requirements, and other unqualified materials must not be used in violation of regulations.
Third, safety technical measures for scaffolding erection and use
1. Scaffolding erection personnel must be qualified professional scaffolders. Employees on duty should have regular physical examinations, and only those who pass the exam can take up the job with a certificate.
2. Scaffolding personnel must wear safety helmets, seat belts, and non-slip shoes correctly. When erecting scaffolding, fences, and warning signs should be set up on the ground, and designated personnel should be assigned to guard them. Non-operators are strictly prohibited from entering.
3. The quality of the components and erection of the scaffolding shall be inspected and accepted, and it shall be used only after passing the inspection.
4. When using scaffolding, the following items should be checked regularly:
① Whether the setting and connection of rods, the structure of connecting wall 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 pole is suspended;
③Whether the fastener bolts are loose;
④ Whether the deviation of the settlement and verticality of the vertical pole meets the regulations;
⑤Whether safety protection measures meet the requirements;
⑥ Whether it is overloaded.
5. During the use of the scaffolding, it is strictly prohibited to remove the following rods:
① Large horizontal bar, small horizontal bar, vertical and horizontal sweeping rods at the main node;
②Wall-connecting parts.
6. When working on the shelf, workers should pay attention to their safety and protect the safety of others to avoid collisions, accidents, and falling objects; it is strictly forbidden to play on the shelf and rest in unsafe places such as sitting on the railings.
7. It is strictly prohibited to stack wood cubes, steel pipes, fasteners, jacks, steel bars, and other construction materials on the cantilever frame.
8. It is strictly prohibited for any team to connect the outer frame to the full hall frame.
9. When erecting the outer frame, it is necessary to ensure that the one-time connection is firm. If there is heavy rain and windy weather and the work needs to be stopped, the stability of the frame must be ensured.
10. Work must be stopped during heavy rain, strong winds, and thunder and lightning weather, and no risky construction is allowed.
11. If the shutdown time is long, when the outer frame is used again, it must be inspected and accepted again before use.
12. The external frame erection must be carried out according to the plan.
Post time: Apr-15-2024