传统地仗处理木梁三面受火后力学性能试验研究

Experimental study on mechanical behavior of timber beams treated with traditional plastering application after exposed to three-side fire

传统地仗层既可作为传统木结构建筑油漆工艺的基层,又能有效防止木构件腐朽和虫蛀,但地仗处理对木构件防火能力影响的研究还很少。通过4组12根木梁受火后力学性能的对比试验,研究了一麻五灰传统地仗工艺对三面受火木梁耐火性能的影响,分析了是否采用一麻五灰、受火时间等参数对木梁极限承载力、初始刚度和炭化速度变化规律的影响。结果表明,一麻五灰传统地仗处理试件在相同受火时间后的极限承载力和初始刚度均明显高于未做表面处理的试件;一麻五灰传统地仗处理和表面无处理木梁试件受火后剩余截面仍基本符合平截面假定;一麻五灰传统地仗处理木梁的炭化速度显著小于未做表面处理的试件,一麻五灰传统地仗处理能有效推迟木梁开始炭化的时间,延缓木梁受火后力学性能的劣化速度。

The traditional plastering layer can act as the base of the painting of the historical timber structures,and can also effectively prevent the wood components from decay and moth-eaten.However,the influence of traditional plastering application on the fire performance of timber beams has not been carefully studied.The influence of traditional one hemp fiber and five plastering application on the fire performance of timber beams was studied through mechanical tests after exposed to three-side fire on 4 series and a total of 12 timber beams.The influence of factors including whether or not treated with traditional one hemp fiber and five plastering application and fire exposure durations on the mechanical behavior such as ultimate bearing capacity,initial stiffness and charring rate of timber beams were analyzed.The results show that both the ultimate bearing capacity and initial stiffness of timber beams treated with traditional one hemp fiber and five plastering are much higher than that of untreated timber beams after exposed to the same fire duration.Timber beams treated with traditional one hemp fiber and five plastering and untreated timber beams basically follows the plane cross-section assumption after exposed to fire.The charring rate of the timber beams treated with traditional one hemp fiber and five plastering application is greatly lower than that of untreated timber beams.Craftwork with traditional one hemp fiber and five plastering application may effectively delay the time to onset of charring,and delay the degradation rate of the mechanical behavior of timber beams after fire.