During a fire, the load-carrying cross section of timber members will reduce due to charring. This article summarizes experimental investigations into the charring rate of different timber species under standard fire conditions, identifies material properties that contribute to the variations of char rates across the different species, and evaluates the applicability of prescribed charring rates to solid timber, cross-laminated timber (CLT), and glulam exposed to standard fires. Data from the literature showed that density had the greatest impact on charring rate. The charring rate of timber decreased with increasing density, particularly timber densities >700 kg/m³. Prescribed charring rates from current design standards provide reasonable estimates of the average charring rate of timber with densities <700 kg/m³ exposed to standard fire curves. A linear charring rate of 0.65 mm/min was found to be suitable for CLT and glulam exposed to a standard fire for up to 180 min if the CLT did not experience char fall-off. The National Design Specification nonlinear charring model may underestimate the char depth of glulam exposed to standard fire curves for longer than 60 min; however, the percent underestimation was small and limited data was available. The review demonstrated the need for data on the char depths of glulam and CLT exposed to standard fire curves for longer than 60 min and particularly for longer than 120 min.

中文翻译：

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不同树种炭化率的回顾

火灾期间，木材构件的承载横截面会因炭化而减小。本文总结了标准火灾条件下不同木材树种的炭化率的实验研究，确定了导致不同树种炭化率变化的材料特性，并评估了规定的炭化率对实木、交叉层压木材的适用性(CLT) 和暴露于标准火灾的胶合木。文献数据表明，密度对炭化率影响最大。木材的炭化率随着密度的增加而降低，特别是木材密度>700 kg/m ³。^{现行设计标准中规定的炭化率可以合理估计密度<700 kg/m 3}暴露于标准火灾曲线的木材的平均炭化率。如果 CLT 没有发生炭脱落，则 0.65 毫米/分钟的线性炭化速率适合暴露于标准火中长达 180 分钟的 CLT 和胶合木。国家设计规范非线性炭化模型可能会低估暴露于标准火曲线超过 60 分钟的胶合木的炭化深度；然而，低估百分比很小，可用数据也有限。审查表明，需要获得暴露于标准火曲线下超过 60 分钟，特别是超过 120 分钟的胶合木和 CLT 的炭深度数据。