What are the maintenance methods for the comb plate expansion device
The maintenance of the comb plate expansion device is the key to extending its service life, ensuring bridge traffic safety and structural stability. It needs to be carried out around the four core goals of "preventing blockage, corrosion, loosening, and timely repair", combined with daily inspections, regular maintenance, and special inspections, to form a full cycle management system. The specif
The maintenance of the comb plate expansion device is the key to extending its service life, ensuring bridge traffic safety and structural stability. It needs to be carried out around the four core goals of "preventing blockage, corrosion, loosening, and timely repair", combined with daily inspections, regular maintenance, and special inspections, to form a full cycle management system. The specific methods are as follows:
1、 Daily inspection (high-frequency basic maintenance, recommended once a week, additional inspection after severe weather)
Daily inspections mainly focus on "visual inspection+simple operation", with a focus on identifying immediate issues that affect the telescopic function. Specific content:
1. Check the cleanliness of the comb teeth gap
Core task: Remove debris such as mud, gravel, fallen leaves, and household waste stuck between teeth (especially after rain or typhoons, debris can easily accumulate with water flow).
Operation method: Use a small shovel, wire brush, or high-pressure water gun (pressure ≤ 0.8MPa, avoid damaging the sealing strip) to clean, ensuring that there is no blockage at the meshing point of the comb teeth - if debris accumulates for a long time, it will hinder the thermal expansion and contraction displacement of the beam body, causing deformation of the comb teeth plate or abnormal stress on the support.
2. Surface flatness and damage inspection
Observe whether there are cracks, dents, and wear on the surface of the comb plate (such as rounded comb teeth, local rusting and peeling of steel plates), and whether there are steps at the connection with the bridge deck (marked if the error is greater than 3mm).
Pay close attention to areas where vehicles frequently brake (such as near bridgeheads and toll stations), where the comb plates wear out faster. If the surface flatness exceeds the standard, it can easily cause vehicle bumps, noise, and even exacerbate comb fatigue damage.
3. Integrity check of sealing strip
Check whether the rubber sealing strip under or on the side of the comb plate is aged, cracked, or detached: The sealing strip is the key to preventing rainwater and impurities from infiltrating the bridge bearings. If it is damaged, it should be temporarily sealed immediately (such as covered with waterproof tape) to avoid corrosion of the bearings.
2、 Regular maintenance (periodic deep maintenance, recommended once every 3-6 months, adjusted according to the environment)
Regular maintenance should be combined with tool detection and targeted handling to solve potential problems that were not discovered during daily inspections. The core content is:
1. Tightness testing and reinforcement of connecting components
The comb plate is connected to the bridge beam/abutment through bolts and anchor bars, and is prone to loosening under long-term vehicle load vibration
Use a torque wrench to check the torque of the fixed bolts (usually 80-120N · m according to design requirements). If the torque is insufficient, it needs to be tightened again; If the bolt corrodes or slides, it is necessary to replace it with a stainless steel or hot-dip galvanized bolt of the same specification (to avoid electrochemical corrosion caused by material mismatch).
Check whether there are cracks at the joint between the anchor bar and the concrete. If cracks appear, they need to be cleaned and repaired by pouring epoxy resin mortar to prevent the anchor bar from loosening and causing overall displacement of the comb plate.
2. Anti corrosion treatment (key measures to extend lifespan)
Regarding the surface of the comb plate: If local rust is found (especially at the edges of the steel plate and bolt holes), it is necessary to first remove the rust (using an angle grinder with a steel wire wheel to polish until the metal color is exposed, or using sandblasting), then apply 2 coats of anti rust primer (such as epoxy zinc rich primer) and 1 coat of topcoat (such as fluorocarbon topcoat), with a coating thickness of ≥ 80 μ m, to ensure isolation from air and moisture.
For stainless steel comb plates: frequent painting is not required, but if salt (coastal bridges) or pollutants adhere to the surface, it should be regularly wiped with a neutral cleaner to avoid pitting corrosion caused by chloride ions.
3. Displacement function test
Choose a date with a large temperature difference (such as high temperature in summer and low temperature in winter), use a feeler gauge or displacement gauge to measure the change in the meshing clearance of the comb plate, and determine whether it can expand and contract normally with the beam body:
If there is no change in the gap (or the change amount is less than 80% of the design value), it may be due to the jamming between the comb teeth or the failure of the sliding support. The sliding surface needs to be disassembled and inspected (such as whether the PTFE plate is worn), and if necessary, the sliding support should be replaced and lubricated with silicone grease.
If the gap is too large (beyond the design value), it may be due to deformation of the comb plate, and it needs to be evaluated whether it needs to be corrected or replaced.
4. Drainage system inspection
There is usually a drainage groove or pipe under the comb plate, and it is necessary to check whether the drainage is unobstructed. If the drainage groove is blocked, it needs to be rinsed with a high-pressure water gun; If the drainage pipe ruptures, it is necessary to replace it with a PVC or metal pipe of the same diameter to prevent rainwater from accumulating in the support area.
3、 Special maintenance (for faults or special situations, non regular, starting immediately upon discovery of problems)
When serious problems are found during daily inspections or regular maintenance, special repairs need to be initiated to prevent the fault from expanding:
1. Comb plate deformation/fracture repair
If there is slight deformation (such as local protrusion) of the comb plate, cold correction can be used (slowly pressing and resetting with a jack and fixture); If there is severe deformation or fracture, it is necessary to cut and replace the damaged unit (note that the material and size of the new unit should be consistent with the original board, and the joint should be welded and polished flat before anti-corrosion treatment).
2. Replace the sealing strip as a whole
If the sealing strip is extensively aged or peeled off (with a damage rate greater than 50%), the old sealing strip should be removed as a whole, and the residue in the slot should be cleaned before inserting a new sealing strip (choose an aging resistant rubber strip that matches the original specifications, such as EPDM rubber, and compact it after embedding to ensure a tight fit with the slot).
3. Special inspection after extreme weather (such as rainstorm, snowstorm, earthquake)
After rainstorm: check whether the drainage system is blocked and whether the support is corroded due to water ingress;
After a blizzard: Remove the ice and snow between the comb teeth (using melting salt, but avoiding salt infiltration into the support, rinse with clean water afterwards), and check whether the comb teeth have deformed due to frost heave;
After the earthquake: Conduct a comprehensive inspection of the displacement of the comb plate, the tightness of the bolts, and the integrity of the anchor bars. If misalignment or cracks occur, the bridge should be immediately stopped and emergency repairs organized.
4、 Maintenance precautions
Safety protection: During maintenance, warning signs (such as reflective cones and warning signs) should be set up at both ends of the bridge. If necessary, some lanes should be closed, and a dedicated person should be arranged to direct traffic to avoid vehicle interference or personnel safety accidents.
Record archiving: Detailed records of the date, content, discovered problems, and handling measures (such as replaced component models and anti-corrosion coating thickness) should be kept for each maintenance, and maintenance files should be established to facilitate subsequent tracking of lifespan and fault prediction.
Material matching: When replacing components such as bolts, sealing strips, and comb teeth units, it is necessary to ensure that they are made of the same material as the original installation (if the original plate is made of Q355 steel, the replacement plate must also be made of the same material); The original sealing strip is made of EPDM, and the new strip cannot be made of ordinary rubber to avoid performance mismatch or accelerated corrosion caused by material differences.
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