关键词: 重组竹, 抗弯强度, 抗弯弹性模量, 特征值

Abstract:

Objective: Bending mechanical test and theoretical analysis of bamboo scrimber were carried out, as well as the suggestions on the characteristic values of bending strength and bending modulus of elasticity (MOE) of bamboo scrimber were put forward. The correlation was fitted to provide technical reference for engineering application. Method: The bending mechanical properties of 40 bamboo scrimber specimens were tested as referred to ASTM D143—14 and other specifications, and their mechanical properties were analyzed in combination with the mid-span displacement curve and the failure modes of each stage. Using statistical theory, the characteristic values of bending strength and bending MOE were obtained by using parametric method, non-parametric method and relevant standard calculation methods respectively. Result: According to the mid-span displacement curve of the specimens, the bending failure of bamboo scrimber occurs in three stages: at the initial stage, the deformation was linear with the load. With the increase of load, the stress of the outermost bamboo fiber in the tensile area reaches the maximum strength and fracture occurs, and the section stiffness decreases. At this time, the specimens are in the elastic-plastic stage. After continuous loading, the cracks developed along the longitudinal and neutral axis of the specimen, and finally the specimen failed after reaching the ultimate load, and no obvious damage was found in the compression area of the specimen. The characteristic values of bending strength calculated using the parametric method are all greater than those calculated using the non-parametric method, and the characteristic values of bending strength calculated using the normal and log-normal distributions are very close, and are all greater than those calculated using the Weibull distribution. For the bending MOE, the characteristic values calculated by the parametric, non-parametric method, and relevant standard are relatively close. Conclusion: From the perspective of accuracy, take the 5% percentile value of non-parametric calculation as the characteristic value of bending strength, and take the 5% percentile of parametric calculation value as the characteristic value of bending MOE. On this basis, the suggested values for bending strength corresponding to different levels of bending MOE of bamboo scrimber were proposed.

Key words: bamboo scrimber, bending strength, bending modulus of elasticity (MOE), characteristic value