What are the applications of plate rubber bearings in highway bridge structures
Rubber bearings are the core supporting components in highway bridge structures, with rubber as the main material and embedded with thin steel plates for reinforcement. They have the characteristics of good elasticity, strong bearing capacity, convenient installation, and economic cost. They are suitable for connecting the upper and lower structures of various highway bridges, and have three main
Rubber bearings are the core supporting components in highway bridge structures, with rubber as the main material and embedded with thin steel plates for reinforcement. They have the characteristics of good elasticity, strong bearing capacity, convenient installation, and economic cost. They are suitable for connecting the upper and lower structures of various highway bridges, and have three main functions: force transmission, shock absorption, and displacement adjustment. They are widely used in mainstream bridge types such as medium and small span highway beam bridges and slab bridges, and are key components to ensure the safe and stable operation of bridges. The specific application scenarios and core functions are as follows:
1、 Core application scenario: Adapt to various types of highway bridge main structure connections
The core application of laminated rubber bearings is the support connection between the upper beam of the bridge and the lower pier/cover beam, which is the "force transmission link" between the two. Different bridge types are adapted to corresponding specifications of bearings, covering the mainstream application scenarios of highway bridges
1. Highway simply supported beam bridge (mainstream application scenario)
Simply supported beam bridge is the most common type of highway bridge, with plate rubber bearings as supporting components, suitable for the installation of prefabricated hollow slab beams, prefabricated T-beams, prefabricated small box beams and other simply supported beam bodies.
Application method: At the bottom of both ends of each span of the beam, corresponding to the top surface of the lower cover beam, symmetrically arrange plate rubber supports. The number of single beam supports is adapted according to the width of the beam (usually 2-4 per beam), forming a stable support system.
Adaptation value: The end of the simply supported beam bridge body needs to freely expand and rotate, and the plate rubber bearings can simultaneously meet the requirements of vertical bearing, horizontal displacement, and angle adjustment, avoiding the obstruction and cracking of beam body expansion. It is suitable for the characteristics of small span, large quantity, and batch construction of highway simply supported beam bridges, with economical cost and convenient installation.
2. Highway continuous beam bridge/continuous rigid frame bridge (auxiliary adaptation scenario)
For continuous beam bridges on small and medium span highways, plate rubber bearings are suitable for supporting non continuous ends (expansion joint ends), while continuous ends are often paired with pot type bearings to form a combined support system.
Application method: Plate rubber bearings are installed at the expansion end (freely expandable section of the beam) of the continuous beam bridge to bear vertical loads and meet the horizontal displacement caused by temperature expansion and concrete shrinkage and creep of the beam. The continuous end adopts bearings with stronger bearing capacity to adapt and fix the requirements.
Adaptation value: Balancing the deformation requirements and support stability of continuous beam bridges, it is more cost-effective than using only basin type bearings and adapts to the stress characteristics of small and medium span continuous beam bridges.
3. Highway slab bridge/solid beam bridge (suitable for lightweight bridge types)
Pedestrian overpasses on highways, rural road slab bridges, and lightweight solid beam bridges should prioritize the use of slab rubber bearings, which are suitable for light loads and small spans.
Application method: Directly installed between the bottom of the slab bridge and the pier, without the need for complex installation procedures. Thin or thick slab rubber bearings can be selected according to the load size of the slab bridge.
Adaptation value: The plate bridge has a light weight and low load, and the plate rubber bearings can meet the bearing capacity requirements. It is also small in size and occupies less land, without increasing the burden on the lower structure. At the same time, it can adapt to the small displacement needs of the plate bridge, with outstanding cost-effectiveness.
4. Highway ramp bridge/interchange auxiliary bridge
The ramp bridges of highway interchanges are mostly small span, curved beam bridges, and the plate rubber bearings are suitable for their light load and small angle displacement characteristics, meeting the requirements of ramp bridge curve layout and small beam displacement.
Core adaptation: There is a slight lateral displacement of the curved ramp beam, and the elastic deformation of the plate rubber support can be compatible with both lateral and longitudinal displacements, avoiding excessive local stress on the beam and ensuring the safety of ramp bridge traffic.
2、 Core functional application: Three key roles in ensuring the safety and stability of bridge structures
Rubber bearings in bridge structures are not simply "load-bearing pads", but achieve three core functions through their own elastic properties, which is an important guarantee for the safety of bridge structures
1. Vertical bearing capacity transmission: core foundation function
All vertical loads such as the upper beam of the bridge, bridge deck pavement, and vehicle loads are transmitted to the lower pier and foundation through plate rubber bearings, and then transmitted to the foundation.
Application logic: The support is embedded with thin steel plates to enhance stiffness and avoid excessive compression deformation of rubber. The support specifications can be correctly matched according to the design load of highway bridges (bearing capacity ranges from tens of kN to thousands of kN), ensuring uniform transmission of vertical loads, avoiding local stress concentration, and preventing pier cracking and beam sinking.
Adaptation requirements: High bearing capacity plate rubber bearings should be used for bridges in heavy-duty sections of highways, while conventional bearing capacity bearings should be used for light-duty bridges on rural highways, and different highway load standards should be adapted as needed.
2. Adjust the displacement of the beam: adapt to the deformation requirements of the bridge and avoid structural damage
During the operation of bridges, two types of deformations occur due to temperature changes, concrete shrinkage and creep, and vehicle load impact. Plate rubber bearings can adapt to their own elastic deformation and serve as a "deformation buffer" for bridges.
Adaptation to horizontal expansion and contraction displacement: When the temperature rises, the beam elongates, and when the temperature decreases, it shrinks. The plate rubber bearing, through the shear deformation of the rubber layer, meets the horizontal displacement of the beam in the longitudinal (along the bridge direction) and transverse (across the bridge direction) directions, avoiding the beam from being "pulled apart" or "squeezed apart", and adapting to the temperature deformation requirements of highway bridges in outdoor environments.
Adaptation of beam rotation angle displacement: When the beam is subjected to load, a small rotation angle will occur at the end. The rubber elasticity of the plate rubber support can be compatible with this rotation angle, ensuring that the support is always in full contact with the beam and the cover beam, without local detachment, and avoiding stress concentration and cracking at the end of the beam.
3. Shock absorption, buffering and isolation: enhance the impact and vibration resistance of bridge beams
Highway bridges are subject to long-term vehicle load impact and road surface vibration. The rubber elasticity of plate rubber bearings can play a role in shock absorption and buffering, while also possessing certain seismic isolation performance.
Impact buffering: The vertical impact load generated by vehicles passing over bridges is absorbed by the elastic rubber layer of the plate type rubber bearings, greatly weakening the impact force and avoiding damage to the lower piers and foundations due to long-term impact, thus extending the service life of the bridge.
Mild isolation: When encountering small earthquakes or strong road vibrations, the elastic deformation of the rubber layer can absorb some of the vibration energy, reduce the impact of vibration on the main structure of the bridge, and improve the safety of highway bridges under complex working conditions.
3、 Segmented specification adaptation application: correctly match according to the requirements of highway bridges
Rubber bearings are subdivided into different specifications based on their structure and performance, and are tailored to meet the different working conditions of highway bridges to ensure their applicability
1. Ordinary plate rubber bearings (most commonly used): suitable for conventional highway bridges
Without any special additional structure, it is composed of alternating vulcanization and bonding of rubber layers and thin steel plates. It is suitable for highway simply supported beam bridges and slab bridges with room temperature, conventional loads, and small displacement. It is a specification with large usage, economical cost, and convenient maintenance.
2. PTFE sliding rubber bearings: suitable for large displacement highway bridges
The top surface of the support is pasted with a PTFE sliding plate, which is matched with the stainless steel plate at the bottom of the beam to significantly reduce the friction coefficient. It is suitable for highway bridges with large expansion displacement of the beam (such as long-span simply supported beam bridges and continuous beam bridges with expansion ends), and avoids damage to the support due to large displacement shear.
3. Cold resistant plate rubber bearings: suitable for highway bridges in cold regions
Made of cold resistant rubber material, it can maintain elasticity even in low temperature environments of -40 ℃, without brittle cracking or hardening. It is suitable for highway bridges in cold northern regions and high-altitude areas, ensuring the normal bearing and displacement functions of bearings in low temperature environments.
4. Seismic resistant plate rubber bearings: suitable for highway bridges in earthquake resistant areas
Rubber material with added seismic additives enhances elastic modulus and shear resistance, suitable for highway bridges in areas with seismic fortification intensity of 6 degrees or above, strengthens the seismic performance of bridges, and avoids bearing detachment and damage during earthquakes.
4、 Application supporting advantages: adapted to the needs of highway bridge construction and operation and maintenance
The application of rubber bearings in highway bridges, in addition to their core functions, also has outstanding advantages in adapting to engineering construction and later operation and maintenance, becoming the bearings for small and medium span highway bridges
Easy to install and suitable for fast construction of highway bridges: The bearings are finished components that do not require on-site processing and can be directly placed and fixed according to the design position. They can be used in conjunction with prefabricated beam lifting for quick installation, greatly reducing the construction period of bridges and adapting to the batch construction needs of highway engineering.
Cost economy and cost control for adapting to highway bridges: Compared with bowl shaped bearings and spherical bearings, the production cost of plate rubber bearings is lower, and the cost budget for adapting to small and medium span highway bridges is higher. It has a higher cost-effectiveness in rural roads and low-grade highways.
Easy to maintain, suitable for long-term operation and maintenance of highway bridges: Under normal use, the service life can reach 15-20 years, and no special maintenance is required on a daily basis. Only regular inspections are needed to check for aging, cracking, and detachment. If damaged, it can be quickly replaced without affecting the normal passage of the bridge, and the operation and maintenance cost is low.
Strong adaptability, suitable for complex highway conditions: It can adapt to outdoor, humid, dusty and other environments of highway bridges, with excellent weather resistance and aging resistance. At the same time, it can customize the size and bearing capacity according to the actual needs of the bridge, with strong adaptability.
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