The characteristic value of compressive strength parallel to the grain is used to design structural members in bridges, houses and buildings. Such value is obtained based on experimental tests. The Brazilian standard proposes equations to estimate the strengths by means of probabilistic equations that allow obtaining the characteristic values of different mechanical strengths, such as the compressive (\(f_{c0,k}\)), tensile (\(f_{t0,k}\)) and shear (\(f_{v0,k}\)) properties obtained from a set of experimental results. Considering the results for these strengths in parallel direction to grain of 30 hardwoods, with a total of 1080 experimental determinations, the precision of the relations proposed by this standard was duly evaluated from probability distribution models. The Normal, LogNormal, Weibull and Exponential functions were used in order to determine the best adhesion model. Once the values and respective models had been determined for each species, a multivariate linear regression model, based on analysis of variance (ANOVA) and dependent on the mean value (\({\bar{x}}\)), coefficient of variation (\(CV\%\)) and lower (LO) and higher (HI) strength values, was adopted to estimate the \(f_{c0,k}\), \(f_{t0,k}\) and \(f_{v0,k}\) adjusted with the most significant terms, in order to infer the quality of the estimator and, consequently, the reliability of such mechanical properties. Finally, the multivariate model proposed here was compared to the empirical proposition of the Brazilian standard, to evaluate the reliability of the model and its adequacy in the estimation of the characteristic strengths values to distinguish the mechanical properties of 30 tropical hardwoods.

中文翻译：

---

热带硬木机械强度评估：概率模型的建议

与晶粒平行的抗压强度的特征值用于设计桥梁，房屋和建筑物中的结构构件。该值是根据实验测试获得的。巴西标准提出了通过概率方程来估算强度的方程，该概率方程允许获得不同机械强度的特征值，例如压缩（\（f_ {c0，k} \）），拉伸（\（f_ {t0， k} \））和剪力（\（f_ {v0，k} \））从一组实验结果获得的特性。考虑到这些强度在平行于30个硬木的方向上的强度结果，总共进行了1080次实验确定，因此从概率分布模型中适当评估了该标准提出的关系的精度。使用法线，对数法线，威布尔和指数函数来确定最佳粘附模型。一旦确定了每个物种的值和相应的模型，便会基于方差分析（ANOVA）并依赖于平均值（\（{\ bar {x}} \）），变异系数来建立多元线性回归模型（\（CV \％\））和较低的（LO）较高的（HI）强度值，用于估算\（f_ {c0，k} \），\（f_ {t0，k} \）和\（f_ {v0，k} \）用最高有效项进行了调整，以推断估计量的质量，并且因此，这种机械性能的可靠性。最后，将此处提出的多元模型与巴西标准的经验命题进行了比较，以评估该模型的可靠性及其在估计特征强度值以区分30种热带硬木力学性能方面的充分性。