清式木结构建筑斗拱耐火性能的试验研究

通过3攒清式木结构斗拱耐火性能的足尺明火试验，研究不同防火处理方式对斗拱耐火性能的影响规律。选取单翘单昂五踩平身科斗拱为研究对象，火源采用木垛火。结果表明：明火试验中，斗拱试件单才瓜拱、单才万拱、厢拱等组件首先被引燃且燃烧持续时间最长，炭化较严重。未进行表面处理的斗拱组件燃烧火焰与木垛火源叠加，火苗高度较高；组件阻燃涂料浸渍的斗拱试件受火过程中组件木材未被引燃。随着受火时间增加，不同位置的温度大部分有不同程度的升高，不同试件距边缘相同位置处的温度变化规律大致相近。各组件沿其轴线方向的炭化不均匀，且各组件炭化速度与空间位置和原始尺寸有关。翘、单才瓜拱、厢拱、单才万拱和外拽枋等组件的宽度和高度方向的炭化速度均较高。表面未处理试件各组件炭化速度为0.5～1.0mm/min，表面喷涂阻燃涂料试件各组件炭化速度为0.1～0.9mm/min，组件采用阻燃涂料浸渍处理试件各组件炭化速度为0.1～0.7mm/min。

Experimental research on fire performance of Dougong of#br# Qing-style timber buildings

To investigate the influence of different fire treatment on the fire performance of Dougong of Qing-style timber buildings, 3 specimens exposed to fire were experimentally studied. The single-qiao-single-ang five-step flat Dougong was tested under the wood crib fire. It is found that the single-cai-gua arch, the single-cai-wan arch and the xiang arch were first ignited and the combustion duration was the longest, resulting in serious charring. The flame of the burning components in untreated Dougong specimen superposed together with the wood crab fire, inducing relative high flame. The components in Dougong specimen with fire retardant coating impregnated materials were not ignited. Temperature at different locations increased with the fire duration time. Different specimens had similar internal temperature development at the same distance to the edge. The charring along the span of the components was not evenly distributed, which depended on their space locations and initial geometry. The charring rate of Qiao, single-cai-gua arch, xiang arch, single-cai-wan arch and external dragging beam at both horizontal and vertical directions was relatively high. The charring rate of specimens without treatment was about 0.5～1.0 mm/min, while that of the specimens with fire retardant coating treatment on the surface was about 0.1～0.9 mm/min. And the charring rate of the specimens with fire retardant coating impregnation of the components was about 0.1～0.7 mm/min.