What are the symptoms of bridge bearing defects?

Bridges are like the skeletal system of the human body, and bearings are the "joints" connecting these "bones." As a bridge engineer with many years of experience, I have witnessed far too many major accidents caused by bearing defects. Today, I will take you on a deeper dive into this often-overlooked "vital point" of bridge construction.

I. Pain Signals (Symptoms) of Bridge Bearings

1. Voiding Symptoms: Obvious gaps appear between the bearing and the beam/pier. Hazard: Equivalent to joint dislocation, leading to abnormal stress concentration. Case Study: A cross-river bridge experienced a 15cm misalignment of the beam due to bearing voiding.

2. Shear Deformation (Common in Rubber Bearings) Symptoms: Wavy, "layered cake"-like protrusions appear in the rubber layer. Data: When the deformation exceeds the design value by 30%, the bearing capacity decreases by 50%.

3. Steel Plate Corrosion (Fatal Flaw in Steel Bearings) Symptoms: "Rust tears" appear on the surface, and anchor bolts corrode into a honeycomb pattern. Case Study: A northern overpass experienced bearing fracture due to chloride corrosion.

4. PTFE Plate Wear (Killer of Sliding Bearings) Characteristics: "Fish scale" pattern appears on the sliding plate surface; if the thickness decreases by more than 2mm, immediate replacement is required.

II. The Truth Behind the Lesions (Cause Analysis)

1. Inherent Design Defects: A cable-stayed bridge suffered from insufficient wind resistance due to incorrect bearing selection. Substandard Materials: Testing revealed that inferior rubber bearings shortened the service life by 60%.

2. Acquired Imbalance: Overloading and Heavy Impacts: A national highway bridge experienced an average of 3,000 overloaded trucks daily. Temperature Stress: In areas with a temperature difference of 50°C, bearing displacement exceeded the design value by 2.8 times. Chronic Corrosion: The salt spray corrosion rate of coastal bridges is 7-10 times that of inland bridges.

3. Lack of Maintenance and Clogged Drainage Systems: Waterlogging accelerated rubber aging. Ten Years Without Maintenance: A bridge bearing was jammed by debris, causing rotational failure.

III. A Shocking Case: A Review of an Accident on a Hangzhou Elevated Bridge In 2019, an inspection revealed: 100% corrosion of the pot bearing anchor bolts. Disassembly revealed: The rubber sealing rings were carbonized and broken. Emergency Treatment: Overnight repairs were carried out using a "lifting + replacement" process.

IV. Prevention Strategies (Engineer Recommendations)

1. A Comprehensive Inspection System: Mandatory items include annual measurement of bearing displacement and quarterly inspection of dust covers. New Technology: 3D laser scanning + AI defect identification system.

2. Targeted Treatment: Temporary measures include stainless steel sheet padding to elevate the detached bearing. Ultimate Solution: Overall lifting and replacement (accuracy must be controlled to 0.1mm level).

3. Preventive Measures: New materials include weathering steel bearings with graphene coating. Smart bearings: Built-in sensors monitor pressure/displacement in real time. Conclusion: Bridge bearing defects are like silent killers; every accident leaves a trace. It is hoped that this article will awaken more people's awareness of the importance of "bridge joints."