学术论文

      火灾条件下落叶松木材抗弯性能研究

      Flexural behavior of larch wood under fire condition

      摘要:
      本文以木建筑结构用材———兴安落叶松为研究对象,考虑实际火灾条件的影响,以 N2为保护气体,开展了木材炭化温度以下(20~280℃)绝氧条件中不同受热时间落叶松木材的抗弯性能试验。结果表明:落叶松木材的密度和含水率随着环境温度的升高而降低,试件质量损失率随着温度的升高而提高;随着环境温度的升高,落叶松木材的颜色逐渐加深,在20~160℃时颜色变化较为缓慢,在190~280℃时变化剧烈;试验范围内,火灾条件中温度(20~280℃)对落叶松木材抗弯强度的影响大于受热时间(60、90和120 min);落叶松木材的抗弯强度和弹性模量随着温度的升高非单调递减,并对相对抗弯强度进行3次多项式拟合,拟合精度较好。
      Abstract:
      At present,the mechanical properties reduction of heated wood between the charring layer and the internal normal wood are ignored during fire design of engineered wood based on the timber structure norms at home and abroad.It is convenient for design calculations;however,it leads to overestimate the strength retention of wood member exposed to fire.In this paper,bending tests of larch wood under different heating time and temperature were carried out,the tests were conducted under the protection of nitrogen according to the impact of actual fire conditions.The results showed that the density and moisture content of all specimens decreased,bending strength,modulus of elasticity and mass loss increased as the temperature increased.As the temperature increased,the color of wood became darker slowly at the temperature ranging from 20 ℃ to 1 60 ℃,and changed rapidly between the 1 90 ℃ and 280 ℃.Among the factors related to the mechanical properties,the effect of temperatures was greater than the heating time.A third order polynomial model,as a function of the temperature,was used to fit the relative bending strength of the specimens,and the result of fitting was accurate enough.
      作者: 杨成 [1] 岳孔 [1] 陆伟东 [1] 刘伟庆 [1] 程秀才 [2] 贾翀 [3]
      Author: YANG Cheng [1] YUE Kong [1] LU Weidong [1] LIU Weiqing [1] CHENG Xiucai [2] JIA Chong [3]
      作者单位: 南京工业大学 土木工程学院,江苏 南京,211800 南京市产品质量监督检验院,江苏 南京,210091 南京林业大学 材料科学与工程学院,江苏 南京,210037
      年,卷(期): 2016, 38(5)
      分类号: S781.29
      在线出版日期: 2016年11月7日
      基金项目: 国家林业公益性行业科研专项(201304504);江苏省高校自然科学研究项目(14KJB220001);江苏省质量技术监督局科技项目