Friction Pendulum Bearing with UHMWPE Sliding Material
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Solution Overview
Problem
Conventional seismic protection systems for buildings are expensive, prone to damage from aftershocks, and require maintenance due to high friction leading to incomplete return to equilibrium position after earthquakes, and are not suitable for retrofitting existing structures.
Innovation Solution
A sliding pendulum bearing with a sliding material exhibiting elasto-plastic compensation behavior, such as UHMWPE, which ensures precise return to equilibrium position by minimizing friction and compensating for geometric deviations, allowing for durable, robust, and maintenance-free earthquake protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional friction bearings are used to dissipate seismic energy, then energy dissipation capacity is improved, but the system fails to return to its original configuration after earthquakes due to high friction
Solution Approach 1:
The patent changes the friction parameter from high to low by using a low-friction thermoplastic resin as the sliding material. This allows the bearing to maintain sufficient energy dissipation capacity while reducing friction enough to enable reliable return to the original configuration after seismic events.
Solution Approach 2:
The patent employs a composite material system consisting of a low-friction thermoplastic resin combined with specific mating materials (such as PTFE or stainless steel) to achieve the optimal balance between energy dissipation and return-to-position capability. The composite material system provides both low friction and adequate damping.
2Reliability
If thermoplastic synthetic resins are used as sliding material, then return to original position is ensured, but geometric deviations and defects negatively impact bearing properties
Solution Approach 1:
The patent incorporates a compliant layer between the thermoplastic resin and the mating material to compensate for geometric deviations and defects before they can negatively impact bearing performance. This cushioning layer accommodates variations in surface geometry and ensures consistent contact.
Solution Approach 2:
The patent modifies the material parameters by selecting thermoplastic resins with specific viscoelastic properties that can accommodate geometric deviations through controlled deformation, thereby maintaining reliable bearing function despite manufacturing tolerances.
3Ease of operation
If sliding shoe presses on thin sliding plate with small load application point, then bearing function is achieved, but settlement trough is created in concrete under long-lasting load
Solution Approach 1:
The patent segments the load path by introducing an intermediate distribution layer between the sliding shoe and the concrete foundation. This layer distributes the concentrated load from the sliding shoe over a larger area of concrete, preventing settlement trough formation while maintaining bearing functionality.
Solution Approach 2:
The patent introduces a compliant intermediate layer that acts as a mediator between the sliding shoe and the concrete foundation. This intermediary layer distributes the contact pressure and prevents direct concentration of loads that would cause concrete settlement.
4Reliability
If conventional seismic protection systems are designed to meet durability and decoupling requirements, then protection performance is improved, but costs become considerable
Solution Approach 1:
The patent employs a cost-effective thermoplastic resin-based bearing design that provides sufficient seismic protection performance at lower cost than conventional systems. The bearing is designed to be replaceable if needed, focusing on providing adequate protection rather than indefinite service life.
Solution Approach 2:
The patent optimizes the bearing parameters (sliding surface geometry, material properties, dimensions) to achieve the required decoupling and durability performance with minimal material usage, thereby reducing costs while meeting protection requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The sliding pendulum bearing effectively dissipates seismic energy, maintains functionality after earthquakes, and can be retrofitted into existing buildings, providing durable and cost-effective seismic protection with low maintenance needs.
Implementation Method 1
The sliding material has elasto-plastic compensation behavior, which in particular has low friction
Implementation Method 2
The sliding material has elasto-plastic compensation behavior, which in particular has low friction
Implementation Method 3
A sliding pendulum bearing with a sliding material exhibiting elasto-plastic compensation behavior, such as UHMWPE, which ensures precise return to equilibrium position by minimizing friction and compensating for geometric deviations
Implementation Method 4
a first sliding plate with a first concave sliding surface and a sliding shoe which is in sliding contact with the first sliding surface of the first sliding plate
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3
AI summary
Disclosed is a friction pendulum bearing (1) for protecting edifices, which is suitable for disconnecting the subsoil (2) from an edifice (3) during movements of the subsoil (2) caused by earthquakes, for example, or as an alternative to conventional deformable bearings. The inventive bearing (1) comprises a first sliding plate (5) with a first concave sliding surface (5') as well as a sliding block (4) that is in sliding contact with the first sliding surface (5') of the first sliding plate (5). A sliding material (9a) that is made of a low-friction plastic having an elastoplastic compensation behavior is enclosed in the sliding block (4), especially ultra-high molecular weight polyethylene (UHMWPE) or polytetrafluoroethylene (PTFE) being used as a sliding material (9a). The sliding block (4) automatically returns to a stable position of equilibrium following a deflection caused by the effect of an external force. The sliding material (9a) has favorable characteristics regarding the absorption of vertical loads, stability, and sliding properties, rendering the same particularly suitable for earthquake protection purposes in structural engineering.