Curved Surface Slider (CSS): Friction Pendulum System (FPS) for Seismic Isolation
Keywords: Curved Surface Slider, CSS, FPS, Friction Pendulum Bearing, TFPB, seismic isolation bearing, lead rubber bearing, LRB
Curved Surface Slider, commonly known as FPS (Friction Pendulum System), is a widely adopted sliding seismic isolator complying with EN15129 standards. Multi-curved surface friction pendulum bearings (TFPB, Triple Friction Pendulum Bearing) belong to advanced CSS series, which are manufactured by Hebei Luze New Material Technology Co., Ltd. to satisfy structural safety demands and protect lives during earthquakes.
I, Working Principle of CSS / FPS
CSS operates based on pendulum mechanics. The core component is the concave curved sliding interface. When seismic excitation occurs, the articulated slider slides along curved surfaces. This motion extends the natural vibration period of buildings and bridges to avoid seismic resonance. Seismic kinetic energy is dissipated via friction between stainless steel plates and high-performance sliding composite materials. Relying on structural gravity and curved geometry, the bearing features reliable self-centering capability, automatically returning to the original position after earthquakes without manual adjustment.
Multi-surface TFPB is the upgraded version of single/double concave FPS. With multiple independent sliding interfaces, it achieves adaptive performance: small earthquakes activate inner sliding surfaces; moderate and large earthquakes trigger multi-layer sliding, realizing graded energy dissipation for near-fault and far-field seismic conditions.
II, Core Differences: CSS-FPS VS LRB / HDR Rubber Bearings
Many engineers confuse friction pendulum bearings with elastomeric isolators such as Lead Rubber Bearing (LRB) and High Damping Rubber Bearing (HDRB). Their essential differences are listed below:
Period characteristic
FPS isolation period depends only on the curvature radius of sliding surfaces, independent of superstructure weight. LRB/HDR period is highly sensitive to vertical load; performance fluctuates when load changes.
Self-centering & durability
CSS relies on gravity for reset. No rubber aging, creep or hardening problems. Rubber bearings suffer long-term creep, ageing and limited service life under outdoor exposure.
Environmental adaptability
FPS works stably under extreme low temperature, ultraviolet exposure and corrosive environments. Rubber materials degrade under harsh climate.
Installation space
FPS has compact vertical height, suitable for projects with limited reserved space. LRB requires larger vertical dimension.
Energy dissipation mode
FPS dissipates energy by surface friction; LRB consumes energy through plastic deformation of lead cores. HDR depends on rubber internal hysteresis.
III, Typical Application Scenarios
Hebei Luze's TFPB multi-curved surface sliders serve stadiums, hospitals, transportation hubs, long-span bridges, high-rise buildings and critical infrastructure. Compared with traditional isolation products, CSS-FPS demonstrates stable performance under large displacement, superior adaptability for heavy-load structures.
Summary
As a mature and advanced seismic isolation solution, Curved Surface Slider FPS overcomes multiple defects of rubber bearings. Multi-surface friction pendulum bearings provide flexible, reliable, long-term seismic protection. For modern earthquake-resilient construction, CSS-FPS is the preferred all-around anti-seismic product to safeguard buildings and human lives.
