Representativeness analysis and apparent density as estimators of modulus of elasticity of class C60 of NBR7190:1997

Abstract For correct dimensioningof wood structures, the premises of the Brazilian standard are extremely valuable as a guide for structural engineers, as it exhibits standard values of resistance. Thus, this study aims to analyze whether the value of the class C60 elasticity module shown in the Brazilian standard matches the values obtained in the test of 23 Brazilian species, using the Bootstrap methodology with 1 million simulations. In addition, it sought to analyze, with regression models, whether it is possible to estimate this rigidity property (E c0 ) of these 23 species as a function of apparent density. Finally, it was possible to conclude that the Brazilian standard overestimates the modulus of elasticity of Brazilian woods, presenting a value almost 35% higher than what actually resists, showing that the standard needs to be revised. Another point was that the regression models do not show significance, in other words, with the apparent density it was not possible to estimate the analyzed rigidity property.

摘要：为实现木结构的精准尺寸设计，巴西标准中的相关规定可为结构工程师提供极具价值的参考依据，因其给出了标准化的抗力取值。据此，本研究旨在通过开展100万次模拟的自助法（Bootstrap），比对巴西标准中C60级木材的弹性模量（modulus of elasticity）取值，与23种巴西本土木材测试所得的弹性模量数值是否相符。此外，本研究还借助回归模型，分析能否以表观密度为自变量，估算这23种木材的该刚度特性（E_c0）。最终研究结论显示：巴西标准高估了本土木材的弹性模量，其给出的数值较实际测试所得值高出近35%，表明该标准亟需修订；另外，回归模型未呈现统计学显著性，即无法通过表观密度估算本次分析的刚度特性。