三面受火胶合木梁耐火极限的试验研究

Experimental Study on Fire Endurance of Glulam Beams Exposed to Three-side Fire

通过5根胶合木梁耐火极限试验,对三面受火胶合木梁的升温规律和耐火极限等进行了详细研究,主要考虑了截面尺寸和荷载比两个参数对其耐火极限的影响。研究结果表明:各测点温度随着受火时间的增加而升高,且停火之后温度下降较慢;测点离木截面表面距离越近,温度越高;且不同试件距边缘相同距离测点温度随时间的变化关系相差较小;相同截面的胶合木梁,随着荷载比的增加耐火极限减小;相同荷载比的胶合木梁,截面较小的木梁耐火极限较低。150 mm×300 mm截面胶合木梁荷载比为0.2、0.35和0.5时,耐火极限分别为46 min、33 min和25 min;而100 mm×200 mm截面胶合木梁荷载比为0.35时,耐火极限为18 min。

The temperature development and fire endurance of glulam beams exposed to three-side fire were carefully studied through the fire endurance test of five glulam beams.The effects of cross-section geometry and load ratio on their fire endurance were considered.Results showed that temperature increased with fire exposure time and decreased very slowly after the fire was stopped.The closer the thermocouples to the surface of glulam beam were,the higher their temperature was.Furthermore,for the thermocouples at different specimens with the same distance to the surface of glulam beam,temperature varied similarly with the fire exposure time.It was observed that for the glulam beams with the same geometry,the fire endurance decreased with load ratios,while for the glulam beams subjected to the same load ratios,the fire endurance decreased with geometry.The fire endurance of glulam beams with the 150 mm×300 mm cross-section tested under the load ratio of 0.2,0.35 and 0.5 were 46 min,33 min and 25 min respectively,while the fire endurance of glulam beams with the 100 mm×200 mm cross-section tested under the load ratio of 0.35 was 18 min.