Durability Assessment of PTFE Bridge Bearing Pads Under Cyclic Loading

Cyclic loading is the most common and long-term working load state of bridge bearing pads. In the whole service cycle of bridges, bearing pads need to bear millions of cyclic alternating loads caused by vehicle passing, pedestrian load, wind vibration and temperature cyclic deformation. Long-term repeated cyclic load will cause fatigue wear, structural creep and performance attenuation of traditional bearing pads, which is the core factor leading to the failure of bridge bearing components. Therefore, durability assessment under cyclic loading is a key link in the performance verification and engineering application of bridge bearing pads. A large number of experimental tests and engineering monitoring data have proved that PTFE bridge bearing pads have far superior cyclic load durability than traditional bearing materials PTFE SHEET.

The excellent cyclic load durability of PTFE bridge bearing pads stems from the stable fluorocarbon molecular structure of PTFE materials. Different from rubber materials that are prone to molecular chain fatigue fracture and plastic deformation under repeated cyclic stress, PTFE molecular bonds have extremely high structural stability and will not produce fatigue aging and creep deformation under long-term low-frequency and high-frequency cyclic loading. In professional cyclic load durability test equipment, PTFE bearing pads have undergone millions of times of alternating compression and sliding friction tests, and the surface structure, friction coefficient and compressive strength have no obvious attenuation, maintaining stable mechanical and tribological properties.

In the durability assessment system, the wear resistance performance under cyclic sliding load is an important evaluation index. Bridge bearing pads will produce reciprocating sliding displacement under the action of temperature deformation and vehicle cyclic load. Traditional bearing pads are prone to abrasive wear and surface roughness increase after long-term reciprocating friction, resulting in increased friction resistance, unsmooth structural displacement and increased bridge internal stress. High-precision PTFE TUBE and sheet sliding layers have ultra-low friction coefficient and self-lubricating performance, which can effectively reduce friction wear under cyclic sliding, keep the sliding surface smooth and flat for a long time, and ensure the long-term stability of bearing friction performance.

Another key assessment index of cyclic load durability is structural compression resilience. Under long-term cyclic compression load, traditional plastic and rubber bearing pads are prone to irreversible compression deformation, resulting in uneven bridge deck force, structural inclination and displacement deviation. Modified PTFE bridge bearing pads have excellent compression resilience and structural toughness. After repeated cyclic compression and load release, they can quickly recover their original structural size and shape without permanent deformation, ensuring the long-term uniform force transmission and stable structural coordination of bridge structures.

Field engineering durability monitoring shows that after more than ten years of on-site cyclic load operation, PTFE bridge bearing pads installed in highway and railway bridges still maintain complete structural integrity and stable working performance, without fatigue failure and performance degradation. Compared with traditional bearing pads which need to be replaced in 5-8 years, PTFE bearing pads have a service life more than twice that of traditional products. The excellent cyclic load durability greatly reduces the later maintenance and replacement cost of bridge engineering, improves the long-term operation safety and stability of bridge structures, and has high engineering application value and economic benefits.