Scaffolding is a working platform erected to ensure the smooth progress of various construction processes. As an almost indispensable part of construction engineering, its erection is crucial to the entire project.
First, Quality Standards for Scaffolding Components
1. Scaffolding Pipes
(1) Steel pipes shall be welded steel pipes of No. 3 steel with an outer diameter of 48mm and a wall thickness of 3.5mm. They shall have product quality certificates and inspection reports. Severely rusted pipes must be replaced and shall not be used for erecting scaffolding.
(2) The surface of the steel pipes shall be straight and smooth, free from cracks, scars, delamination, misalignment, hard bends, burrs, indentations, and deep scratches. Pipes with severe rust, bending, flattening, damage, or cracks shall not be used.
(3) Steel pipes shall be coated with anti-rust paint. Uprights and horizontal bars shall be painted with yellow anti-rust paint, and scissor braces and handrails shall be painted with alternating red and white paint. The maximum weight of each steel pipe shall not exceed 25Kg. Drilling holes in the steel pipes is strictly prohibited.
(4) The steel pipe length of the uprights and longitudinal horizontal bars (large horizontal bars) is 3-6 meters, the steel pipe length of the transverse horizontal bars (small horizontal bars) is 1.1-1.3 meters, and the steel pipe length of the transverse diagonal braces is 3-4 meters.
2. Scaffolding Couplers
(1) New couplers should have a production license, product quality certificate, and inspection report. Used couplers should be inspected before use; those with cracks or deformation are strictly prohibited from use, and bolts with stripped threads must be replaced. Both new and old couplers should be rust-proofed. Couplers with severe rust or damage should be repaired and bolts replaced promptly. Bolts should be oiled to ensure ease of use.
(2) The contact surface between the coupler and the steel pipe should be in good contact. When the coupler clamps the steel pipe, the minimum distance at the opening should be less than 5mm. The couplers used should not be damaged when the bolt tightening force reaches 65 N·m.
Second, Scaffolding Erection Procedures, Methods, and Requirements
(First) Scaffolding Structure
This project uses 16# I-beam cantilevered single-upright double-row external scaffolding. The cantilevered scaffolding has a step distance of 1.8m, a vertical spacing of 1.5m for uprights, and a spacing of 0.85m between inner and outer rows of uprights; small horizontal bars are placed below the large horizontal bars, with an outer large horizontal bar spacing of 0.9m and an inner large horizontal bar spacing of 1.8m. An additional horizontal bar is added in the middle of the small horizontal bars.
(Second) Scaffolding Erection Procedures
1. Placement of Cantilever Beams
(1) The lifting rings of the cantilever beams are pre-embedded according to the plan requirements, with accurate positions and appropriate dimensions.
(2) Laying out and positioning according to the longitudinal and transverse spacing requirements of the scaffolding.
(3) Place the cantilever I-beams one by one. After the I-beams are placed and positioned by a guideline, they are anchored by welding with reinforcing bars.
(4) When hoisting the cantilever beam, handle it gently to minimize the impact on the structural safety of the concrete.
2. Scaffolding Erection Sequence.
Start from one corner of the building and erect uprights one by one → Place longitudinal ground-level bracing (the large horizontal bar close to the cantilever beam), and immediately fasten it to the uprights → Install transverse ground-level bracing (the small horizontal bar close to the cantilever beam), and fasten it to the uprights → After erecting 3-4 uprights, install the first step of the large horizontal bar (ensuring it is fastened to each upright) → Install the first step of the small horizontal bar (fastened to the large horizontal bar) → Install wall ties (or temporary bracing) → Install the second step of the large horizontal bar → Install the second step of the small horizontal bar → Install the third and fourth steps of the large and small horizontal bars → Add wall ties at the corresponding positions → Connect each upright (each 6m in length) → Add scissor bracing and transverse diagonal bracing → Erect waist handrails and toe boards → Fully lay the bottom layer of scaffold boards → Hang safety nets (including horizontal and vertical nets).
3. Scaffolding Erection Precautions
(1) Before fixing the bottom of the uprights, use a plumb line to ensure the uprights are vertical.
(2) After correcting the verticality of the uprights and the horizontality of the main horizontal members to meet the requirements, tighten the coupler bolts to form the starting section of the scaffolding. Continue erecting in the above-mentioned order until the first step of the scaffolding is completed. After each step of scaffolding is erected, check the step distance, longitudinal distance, transverse distance, and verticality of the uprights to ensure they meet the requirements. Then install wall ties and erect the next step.
(3) Scaffolding must be erected in accordance with the construction progress. The height of each erection should not exceed two steps above the adjacent wall ties.
(Third) Scaffolding Erection Methods and Requirements
1. Requirements for Ground-level Stirring.
Longitudinal ground-level stirrings are fixed to the uprights no more than 100mm from the top of the base using right-angle couplers. Transverse ground-level stirrings are fixed to the uprights immediately below the longitudinal ground-level stirrings using right-angle couplers.
2. Requirements for Upright Erection.
(1) The steel pipes used for uprights must be coated with anti-rust paint, and bent steel pipes are not permitted. Uprights must extend at least 1.5-1.8m above the working surface.
(2) Detailed procedures for upright joints.
Uprights must be joined using a butt joint method. The butt joint fasteners on the uprights should be staggered. Joints between two adjacent uprights should not be located in the same step. The vertical distance between the joints of two adjacent uprights should not be less than 500mm, and the distance from the center of each joint to the main node should not be greater than 1/3 of the step distance.
3. Requirements for Horizontal Brace Erection
(1) Horizontal braces are installed inside the uprights and fixed to them with right-angle fasteners. Their length should not be less than three spans. In the same step of the scaffolding, the horizontal braces should form a complete circle around the perimeter and be fixed to the uprights at the inner and outer corners.
(2) Detailed Construction of Main Horizontal Bar Joints: Main horizontal bars should use butt joints. Butt joints should be staggered and not located in the same span or at the same time. The horizontal distance between adjacent joints should not be less than 500mm, and the distance between a joint and a nearby upright should not exceed 1/3 of the upright spacing.
4. Requirements for Erection of Small Horizontal Bars
A small horizontal bar must be installed at the main node (intersection of the upright and the main horizontal bar), and fastened to the upper part of the main horizontal bar with a right-angle coupler. The outer end should extend at least 100mm, and the end extending towards the wall should extend at least 200mm. The distance to the wall finish should not exceed 100mm. The distance between the bar’s axis and the main node should not exceed 150mm.
5. Coupler Installation Requirements:
(1) Coupler specifications must be the same as the outer diameter of the steel pipe.
(2) The tightening torque of the coupler should be 40-50 N·m, and should not exceed 60 N·m. Each coupler must meet the requirements. (3) The distance between the center points of the right-angle couplers and swivel couplers used to fix small horizontal bars, large horizontal bars, scissor braces, and horizontal diagonal braces at the main nodes should not exceed 150mm.
(4) The opening of the butt coupler should face the inside of the scaffold, and the opening of the right-angle coupler should not face downwards.
(5) The length of each member’s end extending beyond the edge of the coupler cover plate should not be less than 100mm.
6. Requirements for the connection between the scaffold and the building structure
(1) Construction form: The connection points are fixed to the pre-embedded steel pipes with steel pipe couplers. The cantilevered horizontal steel beams are connected to the building with steel wire ropes. The tie rods must be set on the uprights and simultaneously hold the inner and outer uprights. The tie rods are arranged horizontally. When they cannot be arranged horizontally, the end connected to the scaffold should be diagonally downwards, not diagonally upwards.
(2) Layout requirements: The wall ties are arranged in two steps and three spans, with a vertical spacing of 3.6m and a horizontal spacing of 4.5m, using double couplers for connection. The scaffolding must be securely connected to the main building structure. When setting up, it should be as close as possible to the main nodes, with a deviation from the main nodes not exceeding 300mm. It must be set up starting from the first horizontal bar at the bottom, using a diamond arrangement.
(3) The fasteners used at the connection points must meet requirements; there should be no loose fasteners or bent embedded steel pipes.
7. Method of Erection of Scissor Bracing
(1) Scissor bracing should be continuously installed along the entire length and height of the scaffolding on the outside. Each scissor bracing connects 5 uprights. Scissor bracing should be erected simultaneously with the uprights, horizontal bars, and small horizontal bars.
(2) The diagonal bracing members are fixed to the extended ends of the intersecting horizontal bars or uprights using swivel couplers. The distance from the center line of the swivel coupler to the main node should not exceed 150mm. In addition to being fastened to the uprights at both ends, the diagonal bracing members should have 2-4 additional fastening points in the middle. The distance between the end of the lowest diagonal bracing member and the upright should not exceed 500mm. The angle between the diagonal brace and the ground should be between 45° and 60°.
(3) For scissor bracing, lap joints should be used, with an overlap length of not less than 1 meter. Three fasteners should be evenly spaced, with the fasteners fastened less than 100mm from the end of the steel pipe.
8. Laying of Scaffold Boards
(1) Scaffold boards should be laid on three small horizontal bars, fully, tightly, and stably, 300mm from the wall.
(2) Laying method: Scaffold boards should preferably be laid flat. Two small horizontal bars must be installed under the joint of scaffold boards laid end-to-end. The overhang length of the scaffold board should be 130-150mm, and the sum of the overhang lengths of the two scaffold boards should not exceed 300mm. When scaffold boards are lapped, the joint must be supported on a small horizontal bar, with an overlap length greater than 200mm, and the overhang length should not be less than 100mm. Scaffold boards at corners must be lapped in a staggered manner. The scaffold planks are fixed to the main horizontal bars with #18 iron wire. At corners and ramp platform openings, the scaffold planks should be reliably connected to the small horizontal bars to prevent slippage.
(3) The construction layer must be fully covered with scaffold planks.
9. Scaffold Internal Enclosure and External Protection
(1) A 900mm high guardrail must be installed on the outer side of each step of the scaffold.
(2) A dense safety net must be continuously installed horizontally from bottom to top on the inner side of the outer uprights of the scaffold.
(3) The outer scaffold must be enclosed every three floors on cantilevered floors. In this project, wooden formwork is used for enclosure.
(Fourth) Quality Requirements for Scaffold Erection
1. Verticality Deviation of Uprights: The verticality deviation of the uprights should not exceed H/300, and 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 main horizontal members: The height difference between the two ends of a main horizontal member must not exceed 20mm, the horizontal deviation of the main horizontal member must not exceed 1/300 of its total length, and the overall flatness deviation must not exceed ±100mm. The height difference between the two main horizontal members in the same span must not exceed 10mm.
3. Horizontal deviation of secondary horizontal members must not exceed 10mm, and the deviation of the overhang length must not exceed -10mm.
4. Deviation of scaffold step distance and horizontal spacing of uprights must not exceed 20mm, and deviation of vertical spacing of uprights must not exceed 50mm.
5. The quantity and position of wall ties must be correct, and the connections must be firm and without looseness.
6. Safety nets must use qualified products and be firmly tied, without damage or incomplete tying.
7. Steel mesh panels must be firmly tied with 18# iron wire, and looseness or protruding panels are strictly prohibited.
8. The I-beams and wire ropes used for cantilever construction must meet the requirements specified in the instructions, and other unqualified materials must not be used in violation of regulations.
Third, Safety Technical Measures for Scaffolding Erection and Use.
1. Scaffolding erectors must be qualified professional scaffolders who have passed the examination. Personnel should undergo regular medical examinations, and only those who pass are allowed to work.
2. Scaffolding erectors must wear safety helmets, safety belts, and non-slip shoes correctly. When erecting scaffolding, the ground should be fenced off, warning signs should be posted, and a dedicated person should be assigned to guard the area. Unauthorized personnel are strictly prohibited from entering.
3. The quality of scaffolding components and the quality of the erection must be inspected and accepted before use.
4. During the use of scaffolding, the following items should be checked regularly:
① Whether the installation and connection of members, wall ties, supports, door trusses, etc., meet the requirements;
② Whether there is water accumulation in the foundation, whether the base is loose, and whether the uprights are suspended;
③ Whether the fastener bolts are loose;
④ Whether the settlement and verticality deviation of the uprights meet the regulations;
⑤ Whether the safety protection measures meet the requirements;
⑥ Whether there is overloading.
5. During the use of scaffolding, the following members must not be removed: ① Main horizontal members and secondary horizontal members at main nodes, longitudinal and transverse ground bracing; ② Wall ties.
6. Workers working on the scaffolding must pay attention to their own safety and the safety of others to avoid collisions, slips, and falling objects; playing on the scaffolding or resting in unsafe places, such as sitting on railings, is strictly prohibited.
7. It is strictly forbidden to pile up construction materials such as timber, steel pipes, fasteners, top supports, and reinforcing bars on cantilevered scaffolding.
8. It is strictly forbidden for any work group to connect the external scaffolding to the full-span scaffolding.
9. When erecting external scaffolding, it is essential to ensure a secure connection in one go. If work needs to be suspended due to heavy rain or strong winds, the stability of the scaffolding must be ensured.
10. Work must be suspended during heavy rain, strong winds, and thunderstorms; no risky construction is permitted.
11. If the work stoppage is prolonged, the external scaffolding must be inspected and accepted again before it can be used again.
12. The erection of external scaffolding must be carried out according to the plan.
Post time: Jan-20-2026