BS 7608 Fatigue (2014)

British Standards Institution

SDC Verifier now includes support for BS 7608:2014 + A1:2015, a widely used UK guideline for fatigue design and assessment of steel structures. This standard defines stress-based evaluation procedures using SN curves, material data, and environmental conditions.

Read the help article on the implementation of BS 7608 Fatigue in SDC Verifier

Objective

BS 7608 sets out a fatigue design methodology based on nominal stress ranges and SN curve classifications. It aims to ensure long-term performance of steel structures under repeated loading by assessing the initiation and propagation of fatigue cracks.

Scope

This standard applies to:

  • Welded and non-welded steel structures
  • Components subject to cyclic loading and fatigue risk
  • Structural elements in bridges, offshore structures, cranes, and general steel construction

Both welded and non-welded details are covered using directional SN curve assignments and classification tables.

Implementation in SDC Verifier

SDC Verifier automates fatigue checks based on BS 7608:2014 through the following features:

✅ Uses yield and tensile strength material data in fatigue life calculations
✅ Applies environment settings (e.g. air by default) as defined in Clause 1.5
✅ Supports directional SN curve classification:  
• X-axis: parallel to the weld  
• Y-axis: perpendicular to the weld  
• Weld intersections use the lowest fatigue class between directions (Clause 12.2)
✅ Implements reduced range adjustment for stress reversals per Clause 15.4 / 16.3.6
✅ Recognizes butt welds and adjusts thickness factor accordingly (Clause 16.3.2)
✅ Option to use Hot Spot Stress values from Weld Finder or Weld Stress tools

All checks are run using rule-based classification tables and project-specific material definitions.

Application

This standard is applicable to fatigue-sensitive projects requiring compliance with UK or international fatigue guidelines. Engineers can:

  • Evaluate structural details using codified SN curves
  • Distinguish fatigue performance based on weld geometry and orientation
  • Automate fatigue life predictions under variable load histories

BS 7608 is particularly relevant for offshore structures, mechanical equipment, and long-span welded steel components with service life exposure to cyclic loading.