Rubber shock absorption bearings for bridges

Plate type rubber support
Type classification
This type of rubber bearing has sufficient vertical stiffness to withstand vertical loads and can reliably transmit the pressure of the upper structure to the piers and abutments; Having good elasticity to adapt to the rotation of the beam end; There is significant shear deformation to meet the horizontal displacement of the upper structure;
Plate supports are divided into two types according to shape: rectangular and circular.
According to whether horizontal displacement can be provided, it is divided into PTFE sliding plate bearings and ordinary rubber bearings.
Rectangular (circular) plate
(1) Performance: This product is made of multi-layer rubber sheets embedded with thin steel plates, bonded and vulcanized under a certain pressure, temperature, and time. Having sufficient vertical stiffness to bear vertical loads and reliably transmit the reaction force of the upper structure of the beam and slab to the piers and abutments, with good elasticity to adapt to the rotation of the beam end; There is also significant shear deformation to meet the horizontal displacement of the upper beam structure.
(2) Features: This product has been widely used in bridge construction, hydropower engineering, and seismic facilities of buildings. Compared with the original steel bearings, it has a simple structure and convenient installation; Save steel and offer low prices; The advantages of simple maintenance and easy replacement, as well as the low building height of this product, are beneficial for bridge design and cost reduction; It has a good isolation effect and can reduce the impact of live loads and seismic forces on buildings.
PTFE sliding plate type
Abbreviated as PTFE sliding plate bridge bearing, this product is made by bonding a layer of 2-3mm thick polytetrafluoroethylene plate onto a regular plate rubber bearing. In addition to the vertical stiffness and elastic deformation of ordinary plate rubber bearings, which can withstand vertical loads and adapt to beam end rotation, the low friction coefficient between tetrafluoroethylene and stainless steel plates at the bottom of the beam( μ≤ 0.03) can make the horizontal displacement of the upper structure of the bridge unrestricted, and large-span bridges with a span of>30 meters, simply supported continuous slab bridges, and multi-span continuous beam bridges can be used as movable supports; Continuous beam pushing, T-beam lateral movement, and large equipment sliding can be used as sliders.
Material classification:
a: Neoprene: applicable temperature:+60 ℃ ~ -25 ℃
B: Natural rubber: Applicable temperature+60 ℃ to -40 ℃
Usage method
1) Selection
a: Check the installation and construction drawings of the plate rubber bearing, mainly paying attention to the specifications, thickness, design bearing capacity, and other main technical parameters of the plate rubber bearing. Attention should also be paid to the size, installation position, and direction of the embedded steel plate for the rubber support of the PTFE sliding plate;
B: When using plate type rubber bearings, the maximum bearing capacity of the bearings should match the reaction force at the bridge support point, and the allowable deviation range should be ± 10%;
c: For curved, sloping, inclined, and wide bridges, circular plate rubber bearings should be selected. It is not suitable to use rubber bearings with spherical crowns or slope shapes in highway bridge engineering;
d: When the longitudinal slope of the bridge is not greater than 1%, the plate type rubber bearing can be directly installed on the pier, but the thickness required for the influence of the longitudinal slope should be considered. When the longitudinal slope gradient is greater than 1%, embedded steel plates (with wedge-shaped steel plates), concrete cushion blocks (with sloping stones), or other measures should be used to level the bottom of the beam to ensure that the support is level. Plate type rubber bearings should be checked according to the relevant regulations of JTG D62 and can only be used after the verification meets the specified requirements.

e: GJZF4 and GYZF4 PTFE sliding plate rubber bearings should be installed horizontally. And upper and lower steel plates should be installed, and 5201-2 silicone grease lubricating oil should be applied between the PTFE sliding plate and the stainless steel plate. After installation, a dust cover must be installed; The PTFE sliding plate of the support shall not be set on the bottom surface of the support, and the stainless steel plate in contact with the PTFE sliding plate shall not be directly set on the bridge pier or abutment pad stone. 2) Installation a: Installation preparation a. 1 The installation site of the plate type rubber bearing should be equipped with supporting pad stones. The plane size of the supporting pad stones should be determined based on local pressure calculation. The length and width of the pad stones should be increased by at least 50mm compared to the corresponding size of the bearing, and their height should be above 100mm, and consideration should be given to facilitating the replacement of the bearing. a. 2. Steel mesh should be arranged inside the cushion stone of the support. When the diameter of the steel bars is 8mm, the spacing should be 50mm × 50mm, there should be vertical steel bars extending into the bearing pad stone inside the bridge pier and abutment, and the concrete strength grade of the bearing pad stone should not be lower than C50. a. The surface of the 3 bearing pad stones should be flat, clean, dry, and free of floating sand. The elevation of the top surface of the support pad stone is required to be accurate and accurate. In the case of flat slopes, the supporting pad stones at both ends of the same beam and the supporting pad stones on the same pier and abutment should be within the same design elevation plane, and their relative height difference should not exceed ± 1.5 mm. The height difference of the same supporting pad stone should be less than 0.5 mm. B: After the support is installed, it should be checked whether there is a manufacturer's trademark or permanent mark on the support. During installation, the centerline of the support position should be marked on both the support pad stone and the support according to the design drawings to ensure accurate positioning of the support. B. During the installation of the 2 supports, it is necessary to prevent the supports from being biased or causing excessive initial shear deformation. After installation, it is necessary to ensure that the support is in close contact with the upper and lower structures, and there must be no detachment. For beams and slabs that do not form a whole, heavy vehicles should be avoided from passing through. B. The design of bridge piers and abutments should consider the need for bearing maintenance and replacement. Under no circumstances shall two or more supports be installed side by side along the longitudinal centerline of the beam at the same support point; On the same beam (plate), it is not advisable to set more than two supports horizontally; Supports of different specifications should not be installed side by side. B. After the installation of the 4 bearings, a comprehensive inspection should be conducted to see if there are any missing bearings, the installation direction and position of the bearings (contact with the embedded steel plate, center line position of the bearings), the specifications and models of the bearings are incorrect, whether temporary fixing facilities are removed, and whether the PTFE sliding plate bearings are filled with silicone oil (it is strictly prohibited to use lubricating oil instead of silicone oil). Once found, adjustments and treatments should be made in a timely manner to ensure the normal operation of the bearings after installation, And record all deviations and abnormalities that occur after the installation of the support. B. Average compressive stress during the use of 5 supports σ C=10 MPa. The volume of the rubber elastomer of the support Eb=2000MPa. Friction coefficient when the support comes into contact with concrete μ= 0.3; Friction coefficient when in contact with steel plate μ= 0.2; Friction coefficient of PTFE plate in contact with stainless steel plate (when adding silicone grease) μ Less than or equal to 0.03, when the temperature is below -25 ℃, μ When the f value increases by 30% and the sliding plate support must be installed, silicone grease should be added to the surface of the PTFE plate.