Cross-laminated timber (CLT) is an innovative engineering wood product made by gluing layers of solid-sawn lumber at perpendicular angles. The commonly used wood species for CLT manufacturing include spruce-pine-fir (SPF), douglas fir-larch, and southern pine lumber. With the hope of broadening the wood species for CLT manufacturing, the purposes of this study include evaluating the mechanical properties of black spruce CLT and analyzing the influence of CLT thickness on its bending or shear properties. In this paper, bending, shear, and compressive tests were conducted respectively on 3-layer CLT panels with a thickness of 105 mm and on 5-layer CLT panels with a thickness of 155 mm, both of which were fabricated with No. 2-grade Canadian black spruce. Their bending or shear resisting properties as well as the failure modes were analyzed. Furthermore, comparison of mechanical properties was conducted between the black spruce CLT panels and the CLT panels fabricated with some other common wood species. Finally, for both the CLT bending panels and the CLT shear panels, their numerical models were developed and calibrated with the experimental results. For the CLT bending panels, results show that increasing the CLT thickness whilst maintaining identical span-to-thickness ratios can even slightly reduce the characteristic bending strength of the black spruce CLT. For the CLT shear panels, results show that increasing the CLT thickness whilst maintaining identical span-to-thickness ratios has little enhancement on their characteristic shear strength. For the CLT bending panels, their effective bending stiffness based on the Shear Analogy theory can be used as a more accurate prediction on their experiment-based global bending stiffness. The model of the CLT bending specimens is capable of predicting their bending properties; whereas, the model of the CLT shear specimens would underestimate their ultimate shear resisting capacity due to the absence of the rolling shear mechanism in the model, although the elastic stiffness can be predicted accurately. Overall, it is attested that the black spruce CLT can provide ideal bending or shear properties, which can be comparable to those of the CLT fabricated with other commonly used wood species. Besides, further efforts should focus on developing a numerical model that can consider the influence of the rolling shear mechanism.

中文翻译：

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黑云杉制造的三层和五层交叉层压木材的弯曲，剪切和压缩特性

交叉层压木材（CLT）是一种创新的工程木产品，它通过将固体锯材的各层以垂直角度粘合在一起制成。用于CLT制造的常用木材种类包括云杉松杉（SPF），道格拉斯杉落叶松和南方松木。为了拓宽用于CLT制造的木材种类，本研究的目的包括评估黑云杉CLT的机械性能，并分析CLT厚度对其弯曲或剪切性能的影响。在本文中，分别对厚度为105 mm的3层CLT面板和厚度为155 mm的5层CLT面板进行了弯曲，剪切和压缩测试，两者均使用2号材料制造。等级的加拿大黑云杉。分析了它们的抗弯或抗剪性能以及破坏模式。此外，比较了黑云杉CLT面板和用其他一些常见木材制成的CLT面板的机械性能。最后，对于CLT弯曲面板和CLT剪切面板，它们的数值模型均已开发并根据实验结果进行了校准。对于CLT弯曲面板，结果表明，在保持相同的跨度/厚度比的同时增加CLT厚度甚至可以稍微降低黑云杉CLT的特征弯曲强度。对于CLT剪力板，结果表明，在保持相同的跨度/厚度比的同时增加CLT厚度对它们的特征剪切强度几乎没有增强。对于CLT弯曲面板，它们基于剪切类比理论的有效弯曲刚度可用作对基于实验的整体弯曲刚度的更准确的预测。CLT弯曲试样的模型能够预测其弯曲特性。尽管可以精确地预测弹性刚度，但是由于模型中缺少滚动剪切机制，因此CLT剪切试样的模型会低估其极限抗剪能力。总体而言，已证明黑色云杉CLT可提供理想的弯曲或剪切性能，可与使用其他常用木材制成的CLT相媲美。此外，应进一步努力开发可考虑轧制剪切机理影响的数值模型。CLT弯曲试样的模型能够预测其弯曲特性。尽管可以精确地预测弹性刚度，但是由于模型中缺少滚动剪切机制，因此CLT剪切试样的模型会低估其极限抗剪能力。总体而言，已证明黑云杉CLT可提供理想的弯曲或剪切性能，可与使用其他常用木材制成的CLT相媲美。此外，应进一步努力开发可考虑轧制剪切机理影响的数值模型。CLT弯曲试样的模型能够预测其弯曲特性。然而，尽管可以精确地预测弹性刚度，但由于模型中缺少滚动剪切机制，因此CLT剪切试样的模型会低估其极限抗剪能力。总体而言，已证明黑色云杉CLT可提供理想的弯曲或剪切性能，可与使用其他常用木材制成的CLT相媲美。此外，应进一步努力开发可考虑轧制剪切机理影响的数值模型。尽管可以精确地预测弹性刚度，但由于模型中缺少滚动剪切机制，因此CLT剪切试样的模型会低估其极限抗剪能力。总体而言，已证明黑色云杉CLT可提供理想的弯曲或剪切性能，可与使用其他常用木材制成的CLT相媲美。此外，应进一步努力开发可考虑轧制剪切机理影响的数值模型。尽管可以精确地预测弹性刚度，但由于模型中缺少滚动剪切机制，因此CLT剪切试样的模型会低估其极限抗剪能力。总体而言，已证明黑云杉CLT可提供理想的弯曲或剪切性能，可与使用其他常用木材制成的CLT相媲美。此外，应进一步努力开发可考虑轧制剪切机理影响的数值模型。