Multiscale structural insights of load bearing bamboo: A computational modeling approach

Bamboo has been widely utilized as a load bearing material in building construction since ancient times by taking advantage of its excellent mechanical performances under loading as well as its low density and rapid growth. Applications of bamboo to engineering, architecture, and infrastructure require an in-depth understanding of the relationship between its morphology and mechanics, including how this regularly spaced segmental structure adapts to taking the applied loads. However, previous research on buckling behavior of structural bamboo considered it as a homogenous tube without multiscale structural features, and no reasonable explanation for the regular segment length was proposed. Here, we have implemented representative volume elements within the framework of finite element analysis to study the mechanical response of a bamboo culm under axial compressive load and systematically investigated how the bamboo's hierarchical structural features (e.g., gradient fiber distribution, periodic nodes, and others) contribute to its compression capacity. We find that column buckling is a critical failure mode that leads to the collapse of the entire structure, which can be disastrous. We observe that the gradient fiber distribution pattern along the radial direction significantly contributes to its strength. We find that the occurrence of fiber deviation at the node region reduces the strength of bamboo. Nevertheless, our results show that structural features such as external ridge and internal diaphragm play the role of reinforcement while the effect is more significant for bamboo than other plants with similar node appearance. Our work provides structural insights into the outstanding mechanics of bamboo. Such information could provide a guide for engineers to predict the material mechanics according to its structure, design bamboo-inspired composite materials, and construct high-performance architectures with bamboo accordingly.