In Europe, strength classes for structural timber and glulam lamellae are defined by minimum requirements of characteristic values of the grade determining properties (GDPs). To fulfill these minimum requirements of characteristic values in the daily production at sawmills, indicating properties (IPs) to GDPs are calculated for each board and based on predetermined limits of the IPs (settings) boards are assigned to the graded class, or rejected. The aims of this paper is to address and discuss two different grading procedures/models that can be applied when settings for IPs that reflects a local board property are derived and to show how the yield in different T-classes depend on the model applied. It is not always that a board’s weakest cross-section is evaluated in a destructive test. An IP representing a local board property can therefore be determined either as the lowest property of the tested part of the board or as the lowest property along the whole board when applied to derive settings. Results presented in this paper show that too low settings and too large yields are obtained when the latter IP is employed. Similarly, IPs reflecting a global board property, like axial dynamic MOE, also give too low settings and too high yield in strength classes. This paper is the second and closing part of a series of two paper on prediction of GDPs and procedures for grading sawn timber into T-classes.

中文翻译：

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锯材抗拉强度的预测：强度等级屈服计算模型

在欧洲，结构木材和胶合板的强度等级由等级决定特性 (GDP) 的特征值的最低要求定义。为了在锯木厂的日常生产中满足这些特征值的最低要求，计算每个板的 GDP 的指示属性 (IP)，并根据 IP（设置）的预定限制将板分配到分级等级或拒绝。本文的目的是解决和讨论两种不同的分级程序/模型，当导出反映本地板属性的 IP 设置时可以应用这些程序/模型，并展示不同 T 级的产量如何取决于所应用的模型。在破坏性测试中评估板的最弱横截面并不总是如此。因此，当应用于导出设置时，代表本地板属性的 IP 可以被确定为板测试部分的最低属性或整个板的最低属性。本文中给出的结果表明，当采用后一种 IP 时，会获得过低的设置和过大的产量。类似地，反映全局板属性的 IP，如轴向动态 MOE，也会在强度等级中给出过低的设置和过高的屈服。本文是关于预测 GDP 和将锯材分级为 T 级的程序的系列两篇论文的第二部分，也是结束部分。本文中给出的结果表明，当采用后一种 IP 时，会获得过低的设置和过大的产量。类似地，反映全局板属性的 IP，如轴向动态 MOE，也会在强度等级中给出过低的设置和过高的屈服。本文是关于预测 GDP 和将锯材分级为 T 级的程序的系列两篇论文的第二部分，也是结束部分。本文中给出的结果表明，当采用后一种 IP 时，会获得过低的设置和过大的产量。类似地，反映全局板属性的 IP，如轴向动态 MOE，也会在强度等级中给出过低的设置和过高的屈服。本文是关于预测 GDP 和将锯材分级为 T 级的程序的系列两篇论文的第二部分，也是结束部分。