In the manufacturing process of cross-laminated timber (CLT), lumber selection and grading are essential steps for the quality control of CLT. In this work, a density-based lumber grading method was preliminarily evaluated for hem-fir CLT manufacturing. Based on the univariate regression model of hem-fir lumber modulus of elasticity (MOE) and its density, a density-based grading model was developed. To identify the effectiveness of the model, 470 pieces of thin hem-fir lumber, were segregated into four grades: E1, E2, E3, and E4 based on their density values. Two 3-ply thin-type customized CLT panels were also fabricated with E2 grade lumber as the parallel layer and E3 grade lumber as the transverse layer. Then, five CLT beam specimens were cut from each panel for flatwise bending test. Comparing the experimental and the theoretical values of the MOE, the relative errors were found to be + 11.95% (using shear analogy theory) and − 7.21% (using gamma theory), respectively. By comparison, for this hem-fir lumber, the accuracy of this density-based grading method is close to that obtained by other means of non-destructive testing. However, it seems to be simpler and more cost-effective for the potential hem-fir CLT manufacturing in some circumstances.

在交叉层压木材（CLT）的生产过程中，木材的选择和分级是CLT质量控制的重要步骤。在这项工作中，初步评估了基于密度的木材分级方法用于下杉木CLT的生产。基于下杉-杉木木材弹性模量（MOE）及其密度的单变量回归模型，建立了基于密度的分级模型。为了确定该模型的有效性，根据密度值将470件下摆杉木薄材分为四个等级：E1，E2，E3和E4。还制造了两块3层薄型定制CLT面板，其中E2级木材为平行层，E3级木材为横向层。然后，从每个面板上切下五个CLT光束样本，以进行水平弯曲测试。比较MOE的实验值和理论值，发现相对误差分别为+ 11.95％（使用剪力类比理论）和−7.21％（使用伽玛理论）。相比之下，对于这种半杉木木材，这种基于密度的分级方法的准确性接近于其他无损检测方法所获得的准确性。但是，在某些情况下，对于潜在的下杉木CLT制造而言，它似乎更简单且更具成本效益。