Figure 1 shows the schematic diagram for the thermal
analysis within structural fire engineering design.
Figure 1 Schematic diagram for heat transfer
Model 
Design charts / Test data 
Simple formulae 
Advanced models 
Complexity 
Simple 
Intermediate 
Advanced 
Heat Transfer Modes 
Conduction 
Convection
Radiation
Conduction 
Analysis ability 
Test results
Standard fire conditions 
Empirical solutions
Standard fire conditions 
Accurate solutions
Any fire conditions 
Member types 
Dependent on available test data 
Mainly steel members 
Any material & construction methods 
Input parameters 
Construction type
Member geometry 
Heat flux or fire curves
Boundary conditions
Member geometry
Material thermal properties 
Solutions 
Crosssectional temperature charts
Tabulated thermal data 
Simple crosssectional temperature profile 
One to threedimensional time & space dependent temperature
profile 
Design tools 
Fire part of Eurocodes
Test/Research reports 
Fire part of Eurocodes
Design guides 
Finite element package 
Design charts/tables 
Spreadsheet 
Computer models 
Heat Transfer
Heat transfer is the science to evaluate
the energy transfer that takes place between material bodies
as a result of
temperature difference. The three modes of heat transfer are
conduction, convection and radiation. The thermal analysis on
structural fire
problems can be divided into two parts:
 The heat transfer by convection and radiation across the
boundary from the fire into structural members;
 The heat transfer by conduction within structural members.
Test Data
The thermal analysis in structural members can
be extremely complex, especially for materials that retain moisture
and have a low thermal conductivity. The simplest method of defining
the temperature profile through the crosssection is to use test
data presented in tables or charts which are published in codes
or design guides. These test data are generally based on standard
fire conditions.
Design Formulae
Simple design equations are presented in codes
and design guides to predict the temperature development of bare
steel. The approach considers both radiative and convective heat
transfer and, although a spreedsheet is required to solve the equation
over the fire duration, it is simple to use. Similar equations
exist for protected steel sections, however the thermal properties
of the proposed protection material are needed, which can be difficult
to obtain.
Computer Models
It is possible to use simple heat transfer models
based on onedimensional heat flow. However, simple computer programs
are needed to solve the heat transfer equations. Alternatively,
advance finiteelement heat transfer models can be used, but this
requires the relevant expertise to ensure the models are applied
correctly and used within their limitations.
