What are the applications of comb plate expansion device in bridge reconstruction
The comb plate expansion device is one of the important types of bridge expansion devices. Its core structure is composed of multiple sets of steel comb plates that mesh with each other. The relative displacement of the comb teeth is used to adapt to the longitudinal, transverse, and vertical displacement of the bridge caused by temperature changes, vehicle loads, foundation settlement, and other
The comb plate expansion device is one of the important types of bridge expansion devices. Its core structure is composed of multiple sets of steel comb plates that mesh with each other. The relative displacement of the comb teeth is used to adapt to the longitudinal, transverse, and vertical displacement of the bridge caused by temperature changes, vehicle loads, foundation settlement, and other factors. In bridge renovation projects, the comb plate expansion device has a wide range of application scenarios due to its strong bearing capacity, smooth driving, wide adaptability, and convenient maintenance, as follows:
1. Expansion and contraction renovation of large-span bridges
Long span bridges (such as cable-stayed bridges, suspension bridges, continuous rigid frame bridges, etc.) have high adaptability requirements for expansion devices due to their large spans and large displacements (longitudinal displacements can reach over 100mm). The comb plate expansion device can effectively absorb large displacement by optimizing the comb length and meshing depth. At the same time, its overall rigid structure can withstand the impact load of heavy vehicles, avoiding early damage caused by displacement exceeding the limit of traditional expansion joints (such as modular joints) on large-span bridges.
Typical application: When the original expansion device of an old bridge fails due to aging or insufficient displacement, it is replaced with a comb plate device to solve the problem of beam expansion obstruction caused by temperature stress.
2. Upgrading and renovating heavy-duty transportation bridges
For bridges that bear heavy vehicles such as trucks and construction machinery (such as industrial area bridges and freight dedicated line bridges), the original expansion device may experience problems such as tooth plate deformation and anchor loosening due to insufficient bearing capacity. The steel comb plate of the comb plate expansion device is made of high-strength steel (such as Q345, Q460), with an overall bearing capacity of over 200kN, which can effectively resist heavy load impact and reduce early damage to the expansion device.
Key points of renovation: By thickening the comb plate and optimizing the anchoring structure (such as using reinforcement technology to fix anchor bolts), the connection strength between the expansion device and the beam body can be improved.
3. Bridge reconstruction with high requirements for bridge deck flatness
In scenarios such as urban main roads, highway bridges, etc. that require high driving comfort, the original expansion device may produce bumps and noise when vehicles pass due to excessive seam width and significant height differences. The comb teeth of the comb plate expansion device mesh with each other, and the bridge deck transition is smooth (the height difference between the top surface of the comb teeth and the bridge deck pavement can be controlled within 1mm), which can significantly reduce vehicle impact noise and improve driving stability.
Applicable scenarios: The renovation of urban landscape bridges and bridges near residential areas should balance functionality and environmental protection (reducing noise pollution).
4. Disease repair of medium and small span bridges
Common diseases of expansion devices in small and medium span bridges (such as simply supported beam bridges and continuous beam bridges) include aging and detachment of rubber strips, deformation of steel sections, and damage to concrete in anchorage zones. The comb plate expansion device has a simple structure and does not require complex embedded parts during installation. It can be directly fixed at the end of the beam with anchor bolts, making it suitable for quick replacement and repair of old bridge expansion devices.
Advantages: Short construction period (single seam renovation usually takes 1-2 days to complete), minimal impact on traffic, especially suitable for bridge repair on busy traffic sections.
5. Adaptive transformation of irregular displacement bridges
Some bridges, due to their special structural forms such as curved bridges and inclined bridges, have lateral displacement or angular displacement in addition to longitudinal displacement. The comb plate expansion device can adapt to longitudinal, transverse, and a small amount of vertical angular displacement simultaneously by designing a multi-directional displacement structure (such as adding sliding supports at the bottom of the comb plate), solving the problem of "jamming" in the expansion device of irregular bridges.
Case: In the renovation of bridges with a skew angle greater than 30 °, traditional expansion devices are prone to damage due to lateral displacement obstruction. After replacing them with comb plate devices, they can flexibly adapt to multi-directional displacement.
6. Anti freezing and anti-skid renovation of bridges in low temperature or rainy areas
In cold regions, the gaps of traditional telescopic devices are prone to snow and ice accumulation, leading to vehicle slippage; In rainy areas, gaps are prone to water accumulation and infiltration into beams, causing steel reinforcement corrosion. The comb teeth of the comb plate expansion device have a small meshing gap (usually 5-10mm), and can be matched with waterproof rubber strips or drainage channels to reduce snow and water accumulation problems; At the same time, the surface of the steel comb plate can be treated with anti slip measures (such as sandblasting and engraving) to enhance winter driving safety.
Improvement measures: Install insulation layer or electric heating device below the comb plate (in extremely cold areas) to further enhance the anti freezing effect.
7. Upgrading and replacing existing expansion devices
When the original bridge expansion device (such as joint filling type, plate rubber expansion device) cannot meet the usage requirements due to design defects or aging, comb plate expansion device is a common upgrade choice:
Alternative joint filling expansion device: solves the problems of easy wear and short service life (usually 1-3 years), and extends the maintenance cycle (comb plate type service life can reach 8-15 years);
Replacing small modular expansion devices: In scenarios with moderate displacement (50-200mm), comb plate installation is simpler, lower in cost, and reduces the frequency of replacing rubber sealing strips in modular devices.
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