How to fix mobile scaffolding during high-altitude operations?
When mobile scaffolding is used for high-altitude operations (usually at a height exceeding 2 meters), fixing is the core safety measure to prevent the scaffolding from tipping or slipping. Targeted fixing methods should be adopted based on the working environment, scaffolding height, and load conditions. The specific operation is as follows:
1、 Basic fixation: Ensure bottom stability
Ground hardening and leveling
Priority should be given to working on hardened surfaces such as concrete and asphalt. For soft surfaces such as soil and sand, steel plates (thickness ≥ 5mm, area ≥ 0.25 ㎡) or wooden scaffolding (thickness ≥ 5cm, length ≥ 60cm) should be laid under each wheel seat to increase the load-bearing area and prevent the frame from sinking and tilting.
Check the verticality of the frame with a level ruler: the deviation of the verticality of the upright pole should be ≤ 1/100 of the total height of the frame (such as a 10 meter high frame, the deviation should not exceed 10cm). Adjust the base screw or shim plate to level it and avoid center of gravity deviation caused by tilting.
Wheel locking and auxiliary fixation
All universal wheels must be fully pressed on the brake and the axle screws must be tightened with a wrench (to prevent the brake from loosening), ensuring that the wheels do not slide relative to the ground (can be tested with a manually pushed frame, and no displacement is considered qualified).
If the homework height exceeds 6 meters or the wind speed is ≥ 5 levels (wind speed>8.0m/s), anti slip wedges (such as rubber pads, wooden wedges) should be added at the contact between the wheel seat and the ground. The wedges should be tightly attached to the side of the wheel to further restrict movement.
2、 Connecting with fixed structures: enhancing overall stability
Rigid connection (preferred recommendation)
Connection point setting: When the height of the frame exceeds 5 meters or there is horizontal thrust on the working layer (such as installing exterior wall components or wind force), rigid connectors (such as steel pipe clamps, U-shaped clamps) should be used every 3-4 meters (vertical direction) and 2-3 spans (horizontal direction) to connect the frame uprights with surrounding fixed structures (such as building walls, concrete columns, steel structure frames).
Connection requirements:
The connection between the connecting piece and the upright pole of the frame, as well as the fixed structure, must be firm (the screws must be tightened without looseness, and the gap between the clamp and the component must be ≤ 2mm);
The connection angle should be perpendicular or slightly inclined towards the direction of force (to avoid horizontal tension causing the connection to break);
It is prohibited to connect with non load bearing structures such as scaffolding and billboards to prevent collapse due to unstable foundations.
Flexible tie (supplementary)
If a rigid connection cannot be achieved (such as temporary work or no fixed structure around), a steel wire rope (diameter ≥ 8mm) or a special tie strap can be used, with one end fixed to the pole node at the top 1/3 height of the frame, and the other end connected to the ground anchor point (such as pre buried anchor, heavy counterweight block), forming a "diagonal tie" (with an angle of 45 ° -60 ° with the ground).
Attention: Each side should have at least 2 knots (distributed vertically), and after tying, a wire tensioner should be used to tighten the steel wire rope to ensure that it is not loose (no obvious shaking when pulled by hand), and the anchor bearing capacity should be ≥ 1.5 times the total weight of the frame.
3、 Strengthening fixed measures for high-risk scenarios
The homework height exceeds 10 meters or involves multiple layers of work
In addition to conventional connection, it is necessary to add horizontal support at the top of the frame (such as densified cross bars, spacing ≤ 1.5m), and set diagonal braces at the four corners of the frame (from the top pole to the ground anchor point, with an included angle of 60 ° with the ground) to form a triangle stable structure and disperse vertical loads and horizontal forces.
If it is a multi-layer work platform (≥ 3 layers), each layer of work should be separately connected to a fixed structure to avoid overall imbalance caused by excessive load on the upper layer.
Fixed in special environments
Outdoor windy weather: When the wind speed is ≥ 6 levels (wind speed>10.8m/s), high-altitude operations are prohibited; If it is necessary to work, windproof cables (at least 4 directions, connected to ground anchor points) should be installed at the top of the frame, and the work height should be lowered (not exceeding 5 meters).
Edge work (such as balconies and roof edges): The outer side of the frame should be rigidly connected to the main structure of the building by at least 2 channels, and protective barriers (with a height of ≥ 1.2 meters) should be installed on the outer side of the bottom of the frame to prevent the frame from shifting when workers or materials fall.
Narrow spaces (such as indoor corridors): Horizontal top supports can be set up on both sides of the walls (such as adjustable screw rods to tighten the walls, with a top support spacing of ≤ 3 meters), and the shaking of the frame can be limited by the wall reaction force.
4、 Fixed checks and contraindications
Check and verify
After the fixation is completed, a load test is required: 2 people stand at the edge of the working layer (simulating partial load) to observe whether the frame is tilted, whether the connecting parts are deformed or have abnormal noise, and whether the wire rope/steel pipe is loose;
Regular review: During the homework period, check every 2 hours (or after encountering strong winds or vibrations) whether the fixing points are loose and whether the wheel brakes are ineffective to ensure continuous stability.
Prohibited Acts
It is strictly prohibited to rely solely on wheel brakes to fix high-altitude operations (especially when the height is greater than 3 meters), and must be connected to the fixed structure;
It is prohibited to use brittle materials such as iron wire and nylon rope as substitutes for specialized tie pieces to avoid stress fracture;
When moving the frame, it must be lowered to the lowest height (≤ 1.5 meters) and all fixed connections must be removed. It is prohibited to push or fix it in a high altitude state.
By implementing the above fixed measures, the risk of tipping of mobile scaffolding during high-altitude operations can be minimized. The core principles are: "bottom locking to prevent slipping, rigid connection to resist overturning, and strong reinforcement to adapt to the environment". Flexible combinations should be used according to actual working conditions to ensure compliance with the requirements of the "Technical Code for Safety of High Altitude Construction Operations" (JGJ80).
