横向振动技术评估结构材抗弯、抗拉和抗压强度

共选择了186根尺寸为38 mm×89 mm×3 658 mm的加拿大针叶树商品材云杉-松-冷杉(SPF)的建筑结构材作为试验材料,探讨采用一种横向振动技术来评估这些规格材的静态抗弯、抗拉和抗压强度的可行性.所有试材均根据ASTM D4761的三分点加载方法测量其抗弯弹性模量,然后按照抗弯弹性模量再将它们均匀分成3组.3组试材在采用横向振动方法获得它们的动态弹性模量Etv后,再分别进行抗弯弹性模量和抗弯强度(ASTM D4761)、抗拉强度(ASTM D4761)和抗压强度(ASTMD198)的测试.试验数据表明,采用横向振动方法得到的动态弹性模量Etv与抗弯弹性模量的相关系数(R2)为0.766,与抗压强度的相关系数R2为0.651,均在0.01水平上呈显著相关.但是,动态弹性模量Etv与抗拉强度之间没有显著的线性关系.本研究结果说明,横向振动方法能够用于预测建筑结构材的静态抗弯、抗压强度.

Evaluation of Bending, Tensile and Compressive Strength of Structural Lumber with Transverse Vibration Technique

The objective of this paper was to investigate the possibility of a transverse vibration technique for assessing static bending,tensile and compressive strength of structural lumbers.A total of 186 pieces of 38 mm by 89 mm by(3 658) mm commercial Spruce-Pine-Fir(SPF) structural lumber from a Canadian sawmill was divided into three matched groups in terms of their modulus of elasticity(MOE) obtained from edgewise-bending tests under three-point loading according to ASTM D4761.The matched groups were then tested with a transverse vibration device to measure the dynamic MOE,followed with tests to determine bending MOE and MOR and tensile strength according to ASTM D4761 and compressive strength according to ASTM D198,respectively.It is found that the correlation coefficients(R~2) are(0.766) between the dynamic MOE and the bending MOE and(0.651) between dynamic MOE and compressive strength.The weaker correlation(R~2=(0.438)) exists between dynamic MOE and bending MOR.However,there was no apparent correlation between tension strength and dynamic MOE.The result demonstrates that the transverse vibration technique can be used to predict bending and compressive properties of structural lumber.