Overview
ISO/TR 15657:2013 - Fire resistance tests: Guidelines for computational structural fire design is a Technical Report from ISO/TC 92 that summarizes advances in understanding structural behaviour in fire and gives guidance for computational structural fire engineering. The report links fire scenarios (primarily standardized heating curves such as the ISO 834 furnace test and characteristic/natural fires) to heat-transfer calculations, elevated-temperature material properties, and structural analysis for the fire limit state. It also discusses the time equivalent methodology for relating natural fires to an equivalent ISO 834 furnace duration.
Key topics
- Design process framework: three-stage approach - fire analysis, heat transfer analysis, structural analysis.
- Fire models: standard (nominal) fires, characteristic/natural fires, zone and parametric models, and basis for time-equivalent relationships.
- Heat transfer models: uniform and non‑uniform temperature distributions (1D, 2D, 3D) and heat flux estimation to structural elements.
- Structural models: single member, sub-frame/assembly, and global structural analysis allowing load redistribution.
- Material properties: thermo‑physical and mechanical behaviour of load‑bearing materials at elevated temperatures and guidance on input data for calculations.
- Combination models: coupling thermal and structural analyses and considerations for structural glass, plastics and resins.
- Performance objectives: life safety, property protection, environmental and heritage protection as drivers for design criteria.
Practical applications
ISO/TR 15657:2013 is intended to support:
- Structural and fire safety engineers performing computational structural fire design and performance‑based assessments.
- Design offices using Eurocodes or national regulations to justify alternative (analytical) fire resistance solutions instead of prescriptive classifications.
- Regulatory authorities and reviewers evaluating analytical fire engineering reports and model assumptions.
- Researchers and model developers benchmarking heat‑transfer and structural response models against accepted guidance.
Typical uses include predicting temperature rise in members under fire, selecting appropriate material input data for elevated-temperature analysis, assessing structural integrity for the fire limit state, and applying time‑equivalent conversions between real fires and standard furnace tests.
Related standards
ISO/TR 15657:2013 is a practical reference for computational structural fire design, emphasizing heat transfer, material behaviour at elevated temperatures, and reliable structural modelling to meet fire safety objectives.