| 摘要: |
| 选取截面尺寸为40mm×90mm的兴安落叶松规格材为研究对象，参照GB 50005—2003对规格材进行目测分级及足尺弯曲测试，依据足尺弯曲性质设定落叶松规格材机械分级的等级边界条件，并对规格材进行机械分级.结果表明：目测分级中高等级规格材（Ⅰc~Ⅲc）的比例相对较高，落叶松规格材的主要降等缺陷为节子、轮裂/干裂和腐朽；以弹性模量为界限指标，可以将落叶松规格材划分为M14，M30和M40这3个强度等级；落叶松规格材等级强度从大到小的排列顺序为：M40,Ⅰc,M30,Ⅲc,Ⅱc,M14；机械分级后的规格材其强度性质更加稳定，规格材的价值得到明显提高.综合比较，中国商品林落叶松规格材更适合机械分级. |
| 关键词: 规格材 目测分级 机械分级 足尺弯曲测试 |
| DOI：10.3969/j.issn.1007 9629.2013.04.033 |
| 分类号: |
| 基金项目:林业公益性行业科研专项项目(201104027)；国际竹藤网络中心基本科研业务费专项项目（1632009003）；中国林业科学研究院院所长基金资助项目（CAFINT2010K01） |
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| Grading of Structural Larch Dimension Lumber |
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LOU Wan li1, REN Hai qing1, WANG Zhao hui1, ZHOU Hai bin1, LUO Xiu qin1, JIANG Jing hui1, GUO Wei2
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1.Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China;2.Institute of Building Environment andEnergy Efficiency, Chinese Academy of Building Research, Beijing 100013, China
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| Abstract: |
| Larch dimension lumber of cross section size 40mm×90mm was chosen to be as the species. The dimension lumber was visually graded according to Chinese standard GB 50005—2003, and then full size bending test was carried out to establish the relationships between different mechanical properties and the grade boundaries for mechanical grading of larch dimension lumber were set. At the end, the mechanical grades of larch dimension lumber were obtained. Through visual grading, a higher proportion of high grade dimension lumber was received, and the major grade reducing defects of larch dimension lumber, such as knots, shake/check and decay were observed. With modulus of elasticity as indicator property, larch dimension lumber could be sorted into three grades: M14, M30 and M40. The grade strength of larch dimension lumber is in sequence as: M40, Ⅰc, M30, Ⅲc, Ⅱc, M14. The strength properties of mechanical grading dimension lumber were more stable, the value of lumber has been significantly improved. Through the comprehensive comparison, Chinese commercial forest of larch is more suitable for mechanical grading. |
| Key words: dimension lumber visual grading mechanical grading full size bending test |
