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一麻五灰是传统木结构中常见的地仗保护做法。通过4组10根采用一麻五灰传统保护处理圆木柱的耐火极限对比试验,研究不同持荷水平、不同直径、是否采用一麻五灰传统保护处理等对圆木柱耐火极限的影响。研究结果表明:对于直径为200mm的圆木柱,当无表面防火处理时,荷载比为30%和50%时耐火极限分别为39.7min和8.7min;当表面采用一麻五灰传统保护处理时,荷载比为30%和50%时耐火极限分别为56.0min和19.9min;对于直径为350mm的圆木柱,当无表面防火处理时,荷载比为30%和50%时耐火极限分别为94.2min和62.5min;当表面采用一麻五灰传统保护处理时,荷载比为30%和50%时耐火极限分别为123.7min和94.7min。可见圆木柱的耐火极限随着持荷水平增加而显著降低,随着直径增加而显著增大;采用一麻五灰传统保护处理后,圆木柱的耐火极限明显增大;一麻五灰传统保护处理能有效降低圆木柱内部的温升梯度,延缓圆木柱开始炭化的时间、降低炭化速度。
One Mahogany is a common practice of protecting battles in traditional wood structures. Through four groups of 10 fire-resistant limit comparative experiments with one traditional protection and five gray as protection, the effects of different holding levels, different diameters, whether or not the traditional one-five ash protection treatment on the fire-resistant limit of round logs were studied. The results show that for the 200mm-diameter circular columns, the fire resistance is 39.7min and 8.7min respectively when the load ratio is 30% and 50%, respectively. When the surface is treated with one hemp and five ash traditional protection , And the fire resistance was 56.0min and 19.9min respectively when the load ratio was 30% and 50%. For the cylindrical column with the diameter of 350mm, the fire resistance was 94.2% when the load ratio was 30% and 50% min and 62.5 min, respectively. When the surface was treated with one hemp and five ash traditional protection, the fire resistance was 123.7 min and 94.7 min when the load ratio was 30% and 50%, respectively. It can be seen that the fire-resistant limit of the log column decreases remarkably with the increase of the holding load, and increases significantly with the increase of the diameter. The fire-resistant limit of the log column increases obviously after the traditional protection treatment of one-ash- The traditional protection treatment can effectively reduce the temperature gradient inside the circular column, slow down the time to start the carbonization of the circular column, reduce the carbonization rate.