Eurocode 3 Fatigue (EN 1993-1-9, 2005)

Eurocode 3 Fatigue (EN 1993-1-9, 2005) is a comprehensive fatigue verification standard for structural steel under repeated stress. Implemented in SDC Verifier, it allows nominal and advanced fatigue assessment based on stress range history, weld class, and safety factors.

Key features include:

• FAT Class setup based on detail category (S-N curves for direct and shear stress ranges)
• Reduced Range and Consequence of Failure input with γ_Mf factors
• Nominal Checks – verifying stress range limits
• Fatigue Checks – summing damage across multiple load groups using Rainflow Counting and Fatigue Groups
• Size effect adjustment via k_S for certain welded details (Annex Tables 8.1–8.10)
• Overall Damage < 1.0 required for compliance

The standard distinguishes between damage-tolerant and safe-life design philosophies, with safety factors tailored to each. Support is also provided for Hot Spot or Weld Stress results as fatigue inputs. The checks combine material fatigue strength with loading cycle history to evaluate structural durability over time.

Fatigue damage is calculated for each load group and summed, including optional overshoot indicators (Root3, Root5), ensuring safe service life under fluctuating stresses.