Why use plate type rubber bearings for highway bridges
Plate type rubber bearings for highway bridges are the core load-bearing components that connect the upper structure (such as beams) and lower structure (such as piers and abutments) of the bridge. Their core value lies in the elastic properties of rubber, which simultaneously achieve the three functions of "load-bearing, displacement adjustment, and shock absorption and buffering", solving the st
Plate type rubber bearings for highway bridges are the core load-bearing components that connect the upper structure (such as beams) and lower structure (such as piers and abutments) of the bridge. Their core value lies in the elastic properties of rubber, which simultaneously achieve the three functions of "load-bearing, displacement adjustment, and shock absorption and buffering", solving the stress and deformation problems of the bridge under complex working conditions such as load, temperature, and settlement, and ensuring the long-term safe and stable operation of the bridge. The specific reasons can be decomposed into the following four points:
1. Efficiently transfer loads to ensure structural load-bearing safety
The self weight of the upper beam body (such as the weight of reinforced concrete beams) and the vehicle driving load (such as the weight of trucks) need to be evenly transmitted to the lower bridge pier/abutment through the support, and then transmitted to the foundation. Plate type rubber bearings are based on the core structure of "alternating bonding and vulcanization of multi-layer rubber and thin steel plates" - rubber provides elastic support, steel plates enhance overall stiffness, and can withstand huge pressure in the vertical direction (the bearing capacity of a single bearing can reach tens to thousands of tons), and can evenly distribute the load, avoiding cracking and settlement of the lower structure due to excessive local stress, ensuring the stability of the bridge load-bearing system.
2. Adapt to bridge displacement and release structural deformation stress
Bridges may experience displacement or rotation due to temperature changes (thermal expansion and contraction), vehicle braking (horizontal thrust), and foundation settlement (uneven settlement) during use
When the temperature rises, the beam elongates, and the support can undergo elastic deformation through rubber, allowing the beam to slide slightly in the horizontal direction (displacement is usually 5-50mm);
When the vehicle brakes, the support can buffer the horizontal thrust and avoid rigid collision between the beam and the bridge pier;
When the foundation settles unevenly, the elasticity of the support can adapt to small angles and reduce cracks in the beam caused by uneven stress.
If rigid supports (such as pure steel supports) are used, the deformation of the bridge will generate huge internal stresses, which can easily lead to cracking of the beam and bridge piers, shortening the service life of the bridge.
3. Shock absorption and buffering enhance driving comfort and structural durability
Vehicle operation, especially heavy trucks, can cause impact vibrations on bridges. If the vibrations are directly transmitted to the bridge structure, it can lead to long-term fatigue damage to components and reduce driving comfort. The rubber layer of the plate rubber bearing has good elasticity and damping characteristics, which can absorb the vibration energy generated by vehicle impact and slow down the transmission of vibration to the beam and bridge pier
Reduce cracks caused by vibration in the beam body and extend the service life of the upper structure;
Reduce the bumpy feeling of the bridge deck and improve the smoothness of vehicle travel (especially on bridges with frequent truck traffic such as national and provincial highways).
4. Low cost, easy to install and maintain, suitable for various working conditions
Compared to other types of bearings such as pot rubber bearings and ball steel bearings, plate rubber bearings have significant cost-effectiveness and practicality advantages:
Low cost: The raw materials (rubber, steel plate) are easily available, the production process is mature, and the unit price is only 1/3-1/5 of that of pot type bearings. It is suitable for large-scale application of small and medium span highway bridges (such as simply supported beam bridges with spans of 10-30m);
Easy to install: small size, light weight (usually tens to hundreds of kilograms per piece), no need for complex lifting equipment, can be fixed on site with bolts, shortening the construction period;
Easy maintenance: Under normal use, the service life can reach 15-20 years. If there is local aging, a single support can be replaced separately without interrupting traffic (or only limiting travel for a short period of time), and the maintenance cost is much lower than that of rigid supports;
Strong environmental adaptability: By adjusting the rubber formula (such as low temperature and aging resistant formula), it can adapt to different climate environments such as severe cold in the north and high temperature and humidity in the south, and has low requirements for the flatness of bridge foundations, with high construction fault tolerance.