SYMPOSIA PAPER Published: 01 January 1961

A Treatise on Theoretical Fire Endurance Rating


For most building materials, the enthalpy-temperature relationship is not linear but contains steep sections at places where latent heat is absorbed as a result of desorption of moisture, dehydration, dissociation, or transformation. Partly associated with these physicochemical changes, and partly independent of them, the thermal conductivity also undergoes considerable variation. These are the main reasons why the usual assumptions are not valid when the heat flow through building elements during fire exposure is to be calculated. A numerical method is described which can be used successfully for solving one-dimensional transient heat flow problems of any complexity. The application of this method to the calculation of temperature history of building elements during fire exposure is illustrated through some examples. In cases where the building element is not subject to thermal disintegration or collapse the numerical heat flow analysis will yield the fire endurance of the building element. In other cases the heat flow analysis must be coupled with a numerical stress-deformation analysis.

Author Information

Harmathy, TZ
National Research Council, Ottawa, Ontario, Canada
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Developed by Committee: E05
Pages: 10–40
DOI: 10.1520/STP39388S
ISBN-EB: 978-0-8031-5678-4
ISBN-13: 978-0-8031-5677-7