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木材是可燃性材料,研究木构件的抗火性能具有重要意义。由于缺乏木结构耐火性能的系统研究,我国现行国家标准《建筑设计防火规范》和《木结构设计规范》基于试验方法,仅给出了各类木构件耐火极限的要求,未给出其计算方法。分别介绍了欧洲规范、美国规范、澳洲规范和加拿大规范的木梁耐火极限计算方法,对比发现各国规范中木梁耐火极限计算方法均基于剩余截面法,但其中木材炭化速度的计算方法不同,且考虑角部倒角效应及温度影响区的范围不同。通过将各国规范耐火极限预测值与试验结果对比,发现基于剩余截面法的木梁耐火极限计算方法能较好地预测木梁的耐火极限,考虑密度对炭化速度影响的欧洲规范和澳洲规范与试验结果更接近,因此建议我国规范中木梁耐火极限计算采用考虑密度影响的剩余截面法。
Wood is a flammable material, research fire resistance of wood components of great significance. Due to the lack of systematic research on the fire resistance of wood structures, the current national standard “Code for Fire Protection of Building Design” and “Code for Design of Wood Structure” are based on the test method, only the requirements of refractory limit of all kinds of wood components are given, and no calculation method is given . The calculation methods of fire resistance limit of wood beam based on European, American, Australian and Canadian standards were introduced respectively. Comparisons were made between the calculation methods of fire resistance limit of wood beams in different countries based on the residual section method. However, the calculation methods of wood carbonization rate were different Consider the corner chamfer effect and the temperature-affected zone in different ranges. By comparing the predicted value of fire resistance in different countries with the test results, it is found that the method of calculating the fire resistance of wood beams based on the residual cross-section method can well predict the fire resistance of wood beams, the European norms that consider the influence of density on the carbonization rate, The result is closer, so it is suggested that the calculation of the refractory limit of Zhongmu beam in China should adopt the residual section method which considers the effect of density.