Charring Depth and Charring Rate of Resak and Jelutong Timber Beams in Two-Dimensional Fire
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Wood is a widely used material in building construction and infrastructure due to its environmental sustainability and economic benefits. However, timber structures are inherently vulnerable to fire hazards because of the combustible nature of wood. When exposed to fire, the strength and stiffness of timber members significantly decrease as a result of the charring process. In fire design for timber structures, charring depth and charring rate are critical parameters used to evaluate fire performance. This study aimed to investigate the charring characteristics, specifically, the charring depth and rate of solid timber from two Malaysian tropical hardwood species, namely Resak (Cotylelobium sp.), with a density of 1019 kg/m³, and Jelutong (Dyera costulata sp.), with a density of 506 kg/m³. Three beams from each species were subjected to a two-dimensional fire exposure for 60 minutes, following the standard fire testing procedure outlined in BS 476-20. The results indicated that Resak exhibited a lower lateral charring depth compared to Jelutong, averaging 25 mm and 45 mm, respectively. However, the bottom-side charring depths were similar for both species, measuring 54 mm for Resak and 53 mm for Jelutong. In terms of charring rate, Resak showed a lower value of 0.48 mm/min, while Jelutong had a higher rate of 0.83 mm/min. Both values fall within the acceptable range specified in Eurocode 5. A clear understanding of timber charring behavior, including both depth and rate, is essential for the safe and effective design of timber structures under fire conditions.
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