BS 5400 is a comprehensive British Standard covering the design and construction of steel, concrete, and composite bridges, including specifications for loads, materials, and workmanship.
It is based on the limit state design principle, as outlined in
ISO 2394 – General principles for the verification of the safety of structures.
🔹 Structure of BS 5400
The standard is divided into multiple Parts:
- Part 1 – General statement
- Part 2 – Specification for loads
- Part 3 – Design of steel bridges
- Part 4 – Design of concrete bridges
- Part 5 – Design of composite bridges
- Part 6 – Materials and workmanship (steel)
- Part 7 – Materials and workmanship (concrete, reinforcement, prestressing tendons)
- Part 8 – Recommendations for concrete materials and workmanship
- Part 9 – Bridge bearings
- Section 9.1 – Design of bridge bearings
- Section 9.2 – Materials, manufacture, and installation of bearings
- Part 10 – Fatigue design
🔹 Important Notes
- Some Parts are mandatory requirement-based specifications, while others are guides of good practice.
- Because of this, BS 5400 should not be incorporated into construction contracts in its entirety.
- However, certain Parts (especially Parts 2, 6, and 7) may be incorporated individually, provided there is no conflict with the contract conditions.
🔹 Design Philosophy
BS 5400 is based on limit state design, which differs from its predecessor:
BS 153 – Steel Girder Bridges
Unlike BS 153 (which followed an allowable stress approach), BS 5400 uses:
- Load factors
- Partial safety factors
- Ultimate and serviceability limit states
Since this represented a major change in philosophy, full comparison between old and new design results required:
- Practical implementation experience
- Empirical calibration studies
These studies allow periodic adjustment of load factors if required.