The charring depth and charring rate of glued laminated timber after a standard fire exposure test

Abstract

The purpose of this study was to investigate the charring depth, charring rate and heat release rate of glued laminated timbers (glulams) made from five softwood species as determined by a standard fire test (CNS12514) and the cone calorimeter method. The results indicated that the average charring depth and charring rate of the bottom sides of specimens were higher than those of the lateral sides in the same specimen and after the same fire exposure conditions. The charring rates of most tested glulam specimens could meet the Eurocode 5 and Australian standard 1720.4. The charring rate in all glulam specimens showed a decreasing order as follows: Taiwania>Japanese cedar>China fir>Douglas fir>Southern pine glulam. Generally, the charring rate of glulam specimens decreases with an increase of density. The correlation coefficient ( r=0.53) for the relationship between the charring rate and density value was not high. However, a high correlation ( r=0.88–0.89) between the charring rate/density and density was found in further analysis. The average heat release rate and the total heat release of tested specimens were (in decreasing order): Taiwania>Japanese cedar>China fir.