Citation

Janssens ML. Fire Mater. 2004; 28(2-4): 199-207.

Copyright

(Copyright © 2004, John Wiley and Sons)

DOI

unavailable

PMID

unavailable

Abstract

To accurately predict the structural performance of a wood member, knowledge is required of the rate at which it chars and the temperature distribution in the residual load-bearing section. The charring rate and temperature distribution can be calculated with a model that predicts the thermal degradation or pyrolysis of wood exposed to a high-temperature environment. More than 50 wood pyrolysis models have been developed since World War II. They range from simple analytical expressions to complex systems of coupled partial differential. equations that describe the heat and mass transfer through wood and char. This paper presents a brief overview of the aforementioned models and provides a more detailed description of a new model. This model is referred to by the acronym CROW (Charring Rate Of Wood). Although the intent was to keep CROW as simple as possible, the model accounts for the four major factors that affect the thermal degradation of wood: dry density of the wood; moisture content of the wood; lignin content of the wood; char contraction. The predictive capability of CROW was evaluated on the basis of ASTM E 119 furnace data obtained for a Douglas fir glulam beam tested under different loads. CROW predictions, with some adjustment for moisture effects, are in reasonable agreement with the measurements. The model will be most useful to predict performance of wood members exposed under thermal conditions that deviate from the standard fire (natural or parametric fires) and/or members that are protected by a membrane.