机械应力分级杉木锯材的顺纹抗拉强度

Tensile Strength Parallel to Grain of Chinese Fir Lumber Graded by Mechanical Stress

以杉木锯材为研究对象,对比了不同强度等级机械应力分级杉木锯材的动态弹性模量范围和试样数,探究了机械应力分级杉木锯材的顺纹抗拉强度概率分布规律,并开展了机械应力分级杉木锯材顺纹抗拉的可靠度分析.结果表明:可基于动态弹性模量对杉木锯材进行机械应力分级,机械应力分级杉木锯材位于主要强度等级材质区域Q_(2)、Q_(3)、Q_(4)的试样数占比超90.0%,其顺纹抗拉强度的最优概率分布为对数正态分布;杉木锯材顺纹抗拉强度设计值明显高于未分级和目测分级杉木锯材.

Taking Chinese fir lumber as the research object,the dynamic elastic modulus range and the number of samples of mechanical stress graded lumber(MSGL)with different strength grades were compared,and the probability distribution and the reliability analysis for tensile strength parallel to grain of MSGL were explored.The results show that mechanical stress grading of Chinese fir lumber can be carried out based on dynamic elastic modulus.The number of samples of MSGL located in the main strength grade areas Q_(2),Q_(3) and Q_(4) exceeds 90.0%,and the optimal probability distribution for tensile strength for MSGL is the lognormal distribution.The design value of tensile strength for MSGL is significantly higher than that of ungraded and visual graded lumber.