SFPE S.02 SFPE Engineering Standard on Calculation Methods to Predict the Thermal Performance of Structural and Fire Resistive Assemblies
This standard provides requirements for the development and use of methods to predict the thermal response of structures using listed fire resistive assemblies to time-dependent thermal boundary conditions imposed by fires.
This standard does not provide design objectives. The design objectives for structural fire resistance shall be determined from the applicable code or as defined by a performance-based design process, subject to the concurrence of the enforcement official, building owner, and other stakeholders.
The purpose of this standard is to provide requirements for calculation methods that provide time-dependent temperature field information resulting from fire exposures required for engineered structural fire design (including structural systems and fire barriers).
The annex of this document provides relevant verification cases which include some or all of the physics of the method that will be used in the final application.
Precisely calculated reference temperatures of 16 cases of bodies have been listed, representing a variety of problems that are relevant in fire safety engineering involving a range of complexities:
- Boundary conditions. Fire exposures of surfaces consist of two independent components, heat transfer by convection dependent on adjacent gas temperature and by radiation dependent on incident radiation. The boundary condition of a fire-exposed structure is generally highly nonlinear as the radiation emitted from surfaces depends on the temperature to the fourth power.
- Geometric effects. In some cases heat transfer to structures can be simplified to 0D (lumped mass) or 1D models, whereas in more complicated cases 2D or 3D models may be needed. Composite assemblies involving multiple materials and voids require special consideration.
- Material effects. Thermal conductivity and specific heat capacity are generally dependent on temperature in fire-exposed structures. Hydroscopic materials such as concrete have latent heat effects due to moisture evaporation. Combustible solids undergo thermal decomposition and materials such as timber undergo charring. Intumescent coatings undergo rapid expansion and changes of thermal properties when subjected to elevated temperatures. Some of these complex material effects are not well understood or possible to model at present and are therefore not addressed in the Standard.
Documentation of the Solutions to the SFPE Heat Transfer Verification Cases Prepared by a Task Group of the SFPE Standards Making Committee on Predicting the Thermal Performance of Fire Resistive Assemblies
In 2012, a Task Group was formed by the SFPE Standards Making Committee for Predicting the
Thermal Performance of Fire Resistive Assemblies to develop a set of verification cases to be
published in the SFPE Standard on the Development and Use of Methodologies for Predicting
the Thermal Performance of Fire Resistive Assemblies. The Task Group compiled existing
verification problems, made modifications to problem statements for consistency and
completeness, developed new verification problems to address physics that were not captured in
existing verification problems, and derived solutions to all cases, ensuring that the published
solution was within an acceptable degree of accuracy.
This report documents the work that was performed by the Task Group to determine the
solutions to the verification cases that appear in the Annex of the Standard. All verification
problems were evaluated by two calculation methods. For problems in which an analytical
solution exists, the analytical solution was compared to a numerical solution to verify the
accuracy of the solution. For problems in which no analytical solution exists, the cases were
modeled by two different numerical methods and the results were compared to demonstrate that
the two methods yield the same result within an acceptable tolerance. Modeling assumptions,
convergence studies, and comparisons between calculation methods are documented in the
report. Input files for numerical models have been archived.