To prevent steel supports from slipping or breaking during use, it is necessary to control the entire process of design, installation, use and maintenance, and develop targeted measures based on material characteristics and stress characteristics. The specific measures are as follows:
1、 Source control during the design phase
Reasonable selection and load verification
Select the appropriate steel support specifications (such as Q235/Q355 steel, H-beam, round steel pipe, etc.) based on actual stress (axial force, bending moment, shear force), ensuring that the bearing capacity margin is ≥ 20% (to avoid overloading).
The focus is on verifying the stability of compression members (aspect ratio λ ≤ 200), the strength of tension members, and the strength of node connections (such as bolt shear resistance and fastener anti slip coefficient ≥ 0.3). It is prohibited to use damaged members with a section weakening of more than 10%.
Optimize node connection design
Rigid connections (such as flange welding+high-strength bolt fastening, bolt grade ≥ 8.8) should be preferred for tension/compression nodes to avoid relying solely on flexible connections such as pins and buckles; Install anti slip devices (such as limit plates and pin locking structures) in areas with high slip risk.
2、 Precision control during installation process
Foundation and support surface treatment
The bottom support surface of the steel support should be flat and hardened (concrete strength ≥ C20), and pre embedded steel plates (thickness ≥ 10mm) or anti slip pads (rubber pad+steel plate combination, friction coefficient ≥ 0.4) should be installed to avoid slippage caused by foundation settlement.
The contact part between the slant support and the ground shall be added with diagonal support, and the support and the ground shall be fixed with expansion bolts (buried depth ≥ 10d, d is the bolt diameter) to ensure that there is no displacement space in both vertical and horizontal directions.
Tightening and calibration of connection parts
Strictly tighten the connecting components according to the drawings during installation: the bolt torque should reach the specified value (such as M20 bolt torque of 300-350N · m), and the fastening degree of the fasteners should be based on the "wrench turning no more than 1/4 turn" standard. After connection, check the gap to ensure it is ≤ 1mm.
Use a total station to calibrate the deviation (≤ 10mm) and perpendicularity (≤ 1/1000 length) of the steel support axis. If the inclination exceeds the limit, it needs to be adjusted immediately to prevent eccentric force from causing fracture.
3、 Monitoring and maintenance of usage process
Real time monitoring and early warning
Install stress sensors (such as strain gauges) and displacement gauges at critical nodes to monitor load changes in real-time (recorded once per hour). When the stress reaches 80% of the design value or the displacement exceeds 5mm, immediately stop loading and investigate the cause.
Regular (daily) visual inspection: Check if the connection parts are loose (abnormal if the bolt has no more than 3 exposed threads), if the weld seam is cracked (if the crack length is ≥ 5mm, it needs to be repaired), and if the rod is bent (if the deflection is ≥ L/500, it exceeds the standard).
Dynamic maintenance and reinforcement
If the bolt is found to be loose, it should be tightened in a timely manner. The cracked part of the weld should be repaired with E5015 welding rod (weld height ≥ base metal thickness). After rust removal, the rusted part should be coated with anti rust paint (dry film thickness ≥ 80 μ m).
When the load changes significantly (such as during construction phase transitions), temporary auxiliary supports (such as double spliced steel supports) are added to disperse the force; After extreme weather (strong wind, rainstorm), conduct a comprehensive inspection and reinforce the loose nodes.
4、 Prohibited operation control
Overloading is strictly prohibited: It is forbidden to attach unrelated loads to steel supports (such as hanging heavy objects or using them as scaffolding load-bearing frames), and the weight of temporarily stacked materials should not exceed 50% of the support bearing capacity.
Avoid external impact: Use flexible slings during lifting (direct binding of steel wire ropes is prohibited) to prevent local deformation caused by collisions; Maintain a safe distance of ≥ 1.5m from steel supports during vehicle and mechanical operations.
Through the above measures, the risk of steel support slip and fracture can be fundamentally reduced, ensuring its stable stress during the construction period. For high-risk scenarios such as deep foundation pit support and large-span scaffolding, a special emergency plan needs to be developed, equipped with backup support components for quick replacement in case of emergencies.
