兴安落叶松结构用规格材强度特征值的研究

摘要

以截面尺寸为40 mm×65 mm,40 mm×90 mm和40 mm×140 mm国产兴安落叶松结构用规格材为研究对象,参照GB 50005-2003《木结构设计规范》的目测分等规则,将其分为Ⅰc,Ⅱc,Ⅲc和Ⅳc这4个等级.根据ASTM D4761-02a对其进行抗弯弹性模量、抗弯强度、顺纹抗拉强度和顺纹抗压强度测试.参照ASTMD2915-03,利用非参数法估计得到国产兴安落叶松结构用规格材的不同强度特征值,结果表明,其强度特征值高于进口云杉-松-冷杉(S-P-F)结构用规格材,通过足尺测试获得结构用规格材强度特征值,改变了GB 50005-2003现有强度特征值由无疵小试样推导而得的历史,同时为获得其他国内树种结构用规格材强度特征值提供了科学方法.%Dimension lumber (cross-sections are 40 mmX65 mm, 40 mmX90 mm and 40 mm X 140 mm, length is 4 000 mm) of Chinese larch(Larix gmelini) was visually graded into I c.Ⅱc, Ⅲ c and Ⅳc according to GB 50005-2003 standard, and was tested according to ASTM D4761-02a. The characteristic values of modulus of elasticity(MOE), modulus of rupture(MOR), ultimate tensile strength(UTS) and ultimate compressive strength(UCS) were estimated using nonparametric statistical analyses according to ASTM D2915-03. The characteristic strength value of Chinese larch is larger than that of Spruce-Pine-Fir (S-P-F) dimension lumber. The characteristic strength value was obtained and deduced from small sample of clear wood in GB 50005-2003, so that the situation was changed. The scientific method for estimating the characteristic strength of dimension lumber can be used to dimension lumber of other species in China.