Fatigue Reliability Assessment for Orthotropic Steel Decks Based on Long-Term Strain Monitoring

Area of Science:

• Structural Engineering
• Bridge Engineering
• Fatigue Analysis

Background:

• Orthotropic steel decks (OSDs) are susceptible to fatigue damage in welded details.
• Assessing long-term fatigue reliability is crucial for bridge safety and maintenance.
• Existing methods may not fully capture the time-dependent nature of fatigue in OSDs.

Purpose of the Study:

• To develop and validate a time-dependent fatigue reliability assessment approach for OSD welded details.
• To utilize long-term strain monitoring data for accurate reliability evaluation.
• To provide insights into the fatigue performance of critical bridge components.

Main Methods:

• Established a fatigue reliability limit function based on Eurocode specifications.
• Quantified stress range uncertainty using lognormal distribution or Gaussian Mixture Model (GMM).
• Calculated fatigue reliability via explicit formula or Monte Carlo simulation.

Main Results:

• Applied the approach to an in-service suspension bridge, evaluating four welded details.
• Demonstrated a significant decrease in reliability indices over the bridge's service life.
• Found that three out of four welded details fail to meet target fatigue reliability within a 100-year lifespan.

Conclusions:

• The proposed time-dependent approach effectively assesses fatigue reliability of OSDs.
• Results highlight potential long-term fatigue risks in critical welded connections.
• Informed decisions on bridge maintenance and repair can be made using this methodology.