Friction Pendulum Bearing(FPB)

The friction pendulum isolation system/bearing is a type of bearing that achieves the isolation function by prolonging the vibration period of the structure through spherical pendulum motion and consuming seismic energy at the sliding interface. It is abbreviated as FPS/FPB. The friction pendulum bearing is a kind of isolation bearing, which includes a lower planar sliding plate, a lower planar sliding block, an upper spherical sliding block, and an upper spherical sliding plate. A planar sliding wear - resistant plate is installed on the bottom surface of the lower planar sliding block, and a spherical sliding wear - resistant plate is installed on the top surface of the upper spherical sliding block. The friction coefficient of the spherical sliding wear - resistant plate is large, so it is also called a curved surface slider isolation device.
As a core equipment for building earthquake resistance and disaster reduction, the friction pendulum isolation bearing effectively blocks the transmission of seismic energy to the upper structure by innovatively integrating the pendulum motion mechanism and the friction energy - dissipation principle.

This product strictly complies with national standards of China such as "Rubber Bearings for Building Isolation" (GB/T 20688) and "Friction Pendulum Isolation Bearings for Buildings" (GB/T 37358 - 2019), and has passed the EU CE certification and the AASHTO LRFD specification test in the United States, ensuring that the product performance reaches the international advanced level.
The product is widely used in engineering fields with extremely high requirements for seismic performance, such as high - rise buildings, bridges, nuclear power plants, and historical and cultural relic buildings.

(I) Materials and Design of Core Components
Upper/Lower Seat Plates: Made of Q345 steel, with a yield strength of ≥345MPa and a tensile strength of ≥490MPa. Ultrasonic flaw detection is carried out to ensure that there are no pores, slag inclusions and other defects inside. The surface is treated by hot-dip galvanizing, and the zinc layer thickness is large than 85μm, meeting the requirements of GB/T 13912 standard, which effectively improves corrosion resistance and extends the service life.
Friction Material: A modified polytetrafluoroethylene (PTFE) composite material is selected, with graphite and copper powder added to enhance the friction performance. The friction coefficient is controlled between 0.02 - 0.05 at room temperature, and the performance is stable in the temperature range of - 40℃~+60℃. The surface roughness Ra≤0.8μm to ensure the flatness of the sliding surface and low - friction characteristics.
Spherical Crown Sliding Surface: Made of ZG270 - 500 cast steel, formed by precision casting process. The surface is quenched, and the hardness reaches HRC45 - 50. The curvature radius error is controlled within ±0.5mm, meeting the design requirements to ensure the accuracy and stability of the pendulum motion.
Pendulum Component: Made of high - strength alloy steel, the structure design is optimized through finite element analysis to ensure that the stress distribution is uniform under extreme working conditions, and the maximum stress value is less than 80% of the material yield strength. The pendulum is connected to the upper seat plate by a pin shaft. The pin shaft is made of 40Cr, quenched and tempered, with a shear strength of ≥800MPa.
(II) Innovative Structural Design
Double - Curved - Surface Friction Pendulum Structure: Adopting a double - curved - surface design. Compared with the traditional single - curved - surface structure, it can effectively increase the motion stroke of the pendulum and improve the isolation efficiency. By adjusting the curvature parameters of the double - curved surface, the natural vibration period and horizontal stiffness of the bearing can be flexibly controlled.
Composite Energy - Dissipation System: Integrating two mechanisms of friction energy - dissipation and rubber elastic energy - dissipation. The friction pendulum components are responsible for consuming high - frequency seismic energy, while the multi - layer rubber bearings absorb low - frequency vibration energy, forming a multi-level energy-dissipation system to improve the energy-dissipation efficiency.
Self - Lubricating System: A micro - nano - scale lubricating coating is set on the surface of the friction material. The lubricant is released through a slow - release technology to ensure that the friction coefficient is stable during long - term use, reducing wear, and extending the service life of the bearing.

The principle of seismic isolation and energy dissipation of the friction pendulum seismic isolation spherical bearing is to use the design of the arc surface to extend the vibration period of the structure, so as to greatly reduce the amplification effect of the structure caused by the earthquake action. And through the friction between the arc surfaces of the bearing, the earthquake energy can be consumed and the input of earthquake energy can be reduced. After the earthquake, its unique arc sliding surface has an automatic reset function, which can effectively limit the displacement of the seismic isolation bearing and make it return to its original position after the earthquake.

I, Advantages.
1), Performance Advantages

• Stable performance: The main material of the friction pendulum isolation bearing is metal, and the processing quality is easy to ensure, with higher reliability.
• Good durability: The relative friction surface materials are stainless steel, PTFE and other materials with excellent durability. The cumulative sliding distance confirmed by experiments is long.
• High bearing capacity: The main material is metal, which can withstand high surface pressure. The bearing capacity of the friction material on the sliding surface is high.
• No damage under large deformation: The large deformation of the friction pendulum isolation bearing is only related to the size of the sliding surface and will not damage the bearing. The large - deformation test can form a bidirectional hysteresis curve.

2), Economic Advantages

• High cost - performance: Under the condition of achieving the same performance goals, it has a more significant cost advantage compared with other isolation devices.
• Low installation cost: During installation, only four bolts are needed to connect the bearing to the upper and lower piers. The operation is simple and fast, reducing labor costs.
• Low inspection cost: After the large - deformation test, the bearing is not damaged and can be continued to be used in the project, reducing the bearing cost.
• No replacement risk: The bearing is repeatedly loaded under large - earthquake displacements, and the hysteresis curves completely coincide without damage, indicating that the bearing can be continued to be used after the earthquake without replacement, reducing subsequent maintenance costs.

3), Design Advantages

• Simple principle: The friction pendulum isolation building can be simplified into a single - pendulum model. Its swinging period only depends on the equivalent radius of curvature and is independent of the building weight.

• Simple design: The friction coefficient value can be directly estimated from the shear - weight ratio of the isolation structure. There is no need to consider the torsional deformation of the isolation layer during the design.
• Simple selection: There is no coupling relationship between the deformation amount and the vertical bearing capacity. After determining the friction coefficient and the equivalent radius of curvature, the analysis can be carried out. The bearing selection is only related to the analysis results and there is no need to recalculate according to the selection results.

II, Disadvantages

• Unable to bear tensile force: Traditional friction pendulum isolation bearings have the same properties in all directions and cannot bear tensile force, which limits their application range. However, there are now some improved technologies and designs trying to overcome this problem. For example, some new - type friction pendulum isolation bearings can achieve a certain degree of tensile capacity through special structures or the addition of auxiliary devices.
• High requirements for manufacturing and installation accuracy: The performance and isolation capacity of the bearing are relatively sensitive to manufacturing accuracy. If there are errors in the manufacturing process, it may affect the performance of its isolation. During the construction and installation process, although there are temporary fixing devices, it is difficult to ensure the installation accuracy under the action of large gravity loads. Initial eccentricity and misalignment may occur, which may deviate from the design theoretical requirements, thereby affecting the isolation effect and even posing potential safety hazards.
• Prone to wear and failure: During the using period, Uneven wear of the sliding surface, molecular cross - linking (adhesion) of the sliding surface and bearing jamming, all these as above may occur. These problems will lead to a decline in the performance of the bearing and may even make it unable to work properly. Moreover, the materials of the core sliding surface part may not be heat - resistant or fire - resistant, and there are certain requirements for the temperature and other conditions of the use environment. At the same time, the isolation layer may be in a humid or temporarily flooded situation, which often causes the non - stainless - steel parts in the friction pendulum isolation bearing to rust, thereby affecting the sliding surface, changing the friction coefficient and resulting in failures.
• High manufacturing cost: Compared with some traditional isolation bearings, the structure of the friction pendulum isolation bearing is relatively complex, and the requirements for materials and manufacturing processes are high, which makes its cost relatively high. Its application may be limited in some cost – sensitive building projects.
• Large product volume: Compared with some other types of seismic isolation bearings, the friction pendulum isolation system usually has a large volume and may be limited when used in some buildings or structures with limited space.

(only recommendation show, it could be OEM or manufactured on request of Clients)
1), Specification Parameter Table

Remark:
The vertical pressure, tensile force and horizontal shear force can all be customized according to the engineering requirements.
Displacement:
The displacement can be adjusted according to actual needs.
Reference displacement: ± 50mm, ±100mm, ±150mm, ±200mm, ±250mm...... Unlimited, but the installation dimensions should be taken into account.
Design rotation angle θ:
The default value is 0.02 rad, and the rotation angle can be adjusted according to the structure.
Seismic isolation period: 2s, 2.5s, 2.8s, 3.5s, 4s, 4.5s, 5.0s.
Applicable temperature range: -40°C to +60°C (Celsius).
Coefficient of friction μ:
The designed normal coefficient of friction of the bearings in this series is not greater than 0.03, and the coefficient of friction for seismic isolation and reduction is not greater than 0.05.

2), The constitutive relationship of the mechanical behavior of the friction pendulum seismic isolation spherical bearing is as follows:

Horizontal force：F= VR ×d+μ·V

Stiffness after yielding：K=VR

Vibration period：T=2π 1g×1R+ud

Equivalent stiffness：K_e=V×( 1R + ud )

Equivalent damping ratio：β_eff = 2π ×1duR+1

In the formula：

V The bearing bears the vertical load,

R Radius of the pendulum spherical surface,

d The swinging displacement of the bearing,

μ The friction coefficient of the bearing.

3), Product type

The friction pendulum seismic isolation spherical bearings can be classified into the following two types according to their structures and functions, and each type can be designed as a unidirectional, bidirectional, omnidirectional or fixed structure for designers to choose from.

3A, LZFP(I) type friction pendulum seismic isolation bearing: It has a simple structure and a clear shock absorption mechanism. It is suitable for structures that have no tensile force and only slide for seismic isolation and reduction during an earthquake.

3B, LZFP (II) type sliding friction pendulum seismic isolation bearing has exactly the same functions as an ordinary spherical bearing during normal use. When an earthquake occurs, when the horizontal force borne by the structure is greater than the shear-off force of the shear bolts, the shear bolts will be sheared off and the limit device will be opened. The bearing will isolate the structure from the foundation through the relative sliding between the arc surfaces, preventing most of the seismic energy from being transferred from the foundation to the structure. This product is applicable to structures that generate displacements due to temperature shrinkage and creep during normal use.

Remark:
1, First Piece Testing
2, PTFE plate: Polyfluortetraethylene plate

(I) Installation Process
1), Foundation Treatment
a) The top surface of the foundation should be flat, with a flatness error of ≤2mm/m. A level gauge is used for accurate measurement.
b) The position error of the embedded bolts should be ≤2mm. A total station is used for positioning to ensure the installation accuracy of the bearing.
c) The strength grade of the foundation concrete should not be lower than C30. After pouring, the strength is tested, and the bearing can be installed only when the strength reaches more than 80% of the designed strength.

2), Bearing Installation Process

 

 

 

 

a) Pre - installation Inspection: Checking the appearance, specification model, factory certificate, inspection report and other materials of the bearing to ensure that the product meets the design requirements. Using a dial indicator to measure the initial height, levelness and other parameters of the bearing and make records.
b) Lifting and Positioning: Use special lifting equipment to slowly lift the bearing to the top surface of the foundation and align it with the embedded bolt holes. Use a jack for fine - adjustment to ensure that the deviation between the center of the bearing and the designed position is ≤3mm and the levelness error is ≤0.5%.
c) Bolt Connection: Use a torque wrench to tighten the bolts according to the designed torque, and the torque error is controlled within ±5%. After the bolt connection is completed, conduct a second measurement to ensure that the bearing installation accuracy meets the requirements.
d) Welding Fixation: For the welding connection method, a symmetric welding process is adopted to control the welding current and speed to prevent the bearing from deforming. After welding, conduct weld flaw detection to ensure that the welding quality meets the requirements.

3), Installation sites pictures

(II) Maintenance Plan

• Daily Inspection

a) Conduct an appearance inspection once a month to check whether there are cracks, wear, rust and other phenomena on the surface of the bearing, and whether the connection parts are loose.
b) Check whether the dust cover is intact. If it is damaged, replace it in time to prevent dust and debris from entering the inside of the bearing.

• Regular Detection

a) Conduct a comprehensive inspection once a year, including measuring parameters such as the vertical compression deformation, horizontal displacement, and rotation angle of the bearing. Use measuring instruments such as total stations and level gauges, and the measurement error is controlled within ±1mm.
b) Conduct a mechanical property test once every 5 years. Select a certain proportion of bearings for laboratory tests to check whether performance indicators such as horizontal stiffness and equivalent damping ratio meet the design requirements.

• Special Situation Handling

a) After experiencing natural disasters such as earthquakes and strong winds, immediately conduct a comprehensive inspection of the bearing. If necessary, conduct emergency detection and evaluation. If the bearing is found to be damaged, promptly organize professional personnel for repair or replacement.
b) When the building use function changes, resulting in significant changes in the upper - structure load or seismic action, re - analyze and check the mechanical properties of the bearing. Determine whether it is necessary to reinforce or replace the bearing according to the check results.

(I) Quality Control System

• Raw Material Inspection: Strictly inspect the main raw materials such as steel, rubber, and friction materials. Each batch of raw materials is required to provide quality certificates and be sampled for re - inspection. The steel is analyzed for chemical composition and tested for mechanical properties, the rubber is tested for physical properties and aging properties, and the friction material is tested for friction coefficient and wear performance.
• Production Process Control: Adopt advanced production equipment and processes, and strictly monitor each production link. Set quality control points for key processes (such as rubber vulcanization, steel plate welding, precision machining, etc.), conduct real - time detection and recording. Establish a product production traceability system to ensure product quality traceability.
• Finished Product Inspection: Each bearing needs to be comprehensively tested before leaving the factory, including appearance quality, dimensional accuracy, mechanical properties and other items. The mechanical property test uses a simulated earthquake loading test device, and the loading test is carried out in accordance with relevant standards to ensure that the product performance meets the design requirements.

(II) Quality Assurance Commitment

The warranty period of this product is 10 years, calculated from the date of product acceptance. During the warranty period, if damage is caused by product quality problems, our company will provide free repair or replacement services.
After the warranty period, our company provides lifelong maintenance services, regularly visits customers, and provides customers with technical support and product maintenance suggestions. If replacement parts are required, they will be charged at cost price.

(III), Testing reports

• The installation of the bearing must be carried out by a construction team with professional qualifications. The construction personnel need to be specially trained and be familiar with the bearing installation process and requirements.
• During the installation process, it is strictly prohibited to perform operations such as hitting and impacting the bearing that may damage the bearing. Do not modify the structure and parameters of the bearing without permission.
• During the transportation and storage of the bearing, it should be placed horizontally to avoid tilting and inversion. The storage environment should be dry and ventilated to prevent moisture and rust.
• Regular maintenance inspections should be carried out strictly in accordance with the requirements of this instruction manual to promptly discover and solve problems. The maintenance records should be properly kept as the basis for product quality traceability.
• If you have any questions about the product use or encounter technical problems, please contact our company's technical service department in a timely manner. We will respond within 24 hours.

Hot Tags: friction pendulum bearing(fpb), China friction pendulum bearing(fpb) manufacturers, suppliers, Viscoelastic Damper, Tuned mass damping Devices, Steel Bearings with Elastic Shock Absorption, Sliding friction dampers, Rubber Bearings with Horizontal Force Dispersion, a velocity dependent damper