Bending and shear properties of compressed Sitka spruce
Bending and shear properties of compressed Sitka spruce
复制标题
DOI：
10.1007/s00226-006-0091-8
复制
发表时间：
2007-02
影响因子：
3.4
通讯作者：
H. Yoshihara;S. Tsunematsu
中科院分区：
文献类型：
--
作者：
H. Yoshihara;S. Tsunematsu
我们用小而透明的锡特卡云杉(Picea sitchenssCarr.)试件研究了压缩木材的弯曲和剪切性能。为了测量弯曲性能，三点弯曲试验是在美国测试和材料学会[ASTM D143-94(2005a)]和日本工业标准[JIS Z2101-94(1994)]中标准化的跨高比为14的情况下进行的。在弯曲试验中，同时测量了荷载、跨中挠度和跨中底部应变，并根据基本梁理论得到了杨氏弹性模数和抗弯强度。分别采用矩形截面试件和侧槽截面试件进行了非对称四点弯曲试验，考察了压缩比对试件抗剪性能的影响，得到了试件的剪切弹性模量和抗剪强度。研究结果表明：(1)由荷载-应变关系决定的杨氏模量随压缩比的增大而增大。然而，当杨氏模数由载荷-挠度关系确定时，这一趋势就被掩盖了。因此，根据载荷-应变关系测量杨氏模数是可取的。(2)压缩比为50%时，土体在纵切向平面内的剪切弹性模量最大，而在压缩比为50%时，纵切向平面内的剪切弹性模量最小。(3)受压对弯剪强度比的影响不大。
We examined the bending and shear properties of compressed wood using small and clear specimens of Sitka spruce (Picea sitchensisCarr.). For measuring the bending properties, three-point bending tests were conducted under the span/depth ratio of 14, which is standardized in the American Society for Testing and Materials [ASTM D143-94 (2005a)] and Japanese Industrial Standards [JIS Z2101-94 (1994)]. In the bending test, the load, deflection at the midspan, and strain at the bottom of the midspan were simultaneously measured, and Young’s modulus and bending strength were obtained by elementary beam theory. For obtaining the shear modulus and shear strength, asymmetric four-point bending tests were conducted using the specimens with rectangular and side-grooved cross sections, respectively, and the influence of the compression ratio on the shear properties was examined. The results are summarized as follows: (1) Young’s modulus increased with increasing compression ratio when it was determined by the load–strain relation. Nevertheless, this tendency was rather obscured when Young’s modulus was determined by the load–deflection relation. Hence, it is preferable that Young’s modulus is measured from the load–strain relation. (2) The shear modulus in the longitudinal–tangential plane was maximum at the compression ratio of 50%, whereas that in the longitudinal–radial plane was minimum at the compression ratio of 50%. (3) The influence of the compression on the bending and shear strength ratio was not significant.