The mechanical properties of wood are affected by member size and loading rate. Axial compression tests with different seismic strain rates and sizes of specimens were carried out to investigate the static and dynamic dimensional effects of Yunnan pine timber. And obtained load-displacement curves, compressive strength, modulus of elasticity, peak strain and Poisson’s ratio. Weibull’s weakest chain theory, Bazant’s law of dimensional effects and Carpinteri’s law of multiple fractal dimensional effects were used to analyze the dimensional effects on the compressive strength of wood, and to establish a wood strength model that takes strain rate effects and dimensional effects into account. The results showed that the compressive strength, elastic modulus, and Poisson’s ratio of Yunnan pine wood exhibit both size and strain rate effects. Under the coupling effect of strain rate effect and size effect, the size effect of Yunnan pine wood strength decreases with increasing strain rate, while the strain rate effect increases with increasing size. A size effect model for compressive strength of wood considering strain rate effect based on three theories and experimental data can well describe the dynamic size effect of Yunnan pine wood strength.

中文翻译：

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考虑地震应变率的云南松轴应力特性尺寸效应研究

木材的机械性能受构件尺寸和加载率的影响。通过不同地震应变率和试件尺寸的轴向压缩试验，研究云南松木材的静态和动态尺寸效应。并获得了载荷-位移曲线、抗压强度、弹性模量、峰值应变和泊松比。利用威布尔最弱链理论、巴赞特尺寸效应定律和卡宾特里多重分形尺寸效应定律分析了尺寸效应对木材抗压强度的影响，建立了考虑应变率效应和尺寸效应的木材强度模型。结果表明，云南松木材的抗压强度、弹性模量和泊松比同时表现出尺寸效应和应变率效应。在应变率效应和尺寸效应的耦合作用下，云南松木材强度的尺寸效应随着应变率的增大而减小，而应变率效应则随着尺寸的增大而增大。基于三种理论和实验数据建立的考虑应变率效应的木材抗压强度尺寸效应模型可以很好地描述云南松木材强度的动态尺寸效应。