轻型木结构建筑外墙火灾蔓延试验研究

Experimental study on fire spread upon exterior wood-frame walls

搭建实体火灾试验平台,对窗口溢出火焰沿木骨架组合外墙竖向蔓延特性进行研究。根据不同的外墙饰面材料及构造设置3种典型的工况,分析火焰蔓延、炭化情况以及不同位置温度随时间的变化。结果表明,对于硅酸钙板作外饰面层且无空腔的构造,外墙火灾蔓延危险性最小;对于带空腔的水泥挂板构造,水泥挂板在火焰高温作用下出现变形和破裂,导致空腔后面OSB板被引燃,火焰和烟气沿空腔向上蔓延;对于带空腔的阻燃木挂板构造,外挂板在窗口火作用下经历了引燃、平缓燃烧、剧烈燃烧三个阶段,最终出现失控的火蔓延。对于带空腔的外墙构造,金属泛水条有助于减缓火灾的竖向蔓延。

Experimental fire tests platform were built to study the effect of external flame ejected from windows on fire spread of ex-terior wood-frame walls.Three typical scenarios were studied by considering different construction details and siding materials.Flame spread,carbonization and temperature change with time at different positions were analyzed.Test results showed that the exterior wall with calcium-silicate siding boards and non-cavity had the best performance.For the exterior wall with fiber-cement siding boards and cavity,the fiber-cement boards would deform and break under the flame exposure,leaving the OSB behind the cavity be ignited and the spread of flame and smoke upward along the cavity.For the exterior wall with fire-retardant wooden siding boards and cavity,it experienced ignition,steady burning and vigorous burning stages,and the fire spread upwards and went out of control.For exterior wall with cavities,the metal flush helped to reduce the vertical fire spread upon exterior walls.