Dowel-bearing strength for engineered bamboo products: Review and data-driven analysis

Engineered bamboo products, represented by laminated bamboo and bamboo scrimber, have attracted increasing attention in sustainable construction. Connections in engineered bamboo structures often rely on bolted joints, for which half-hole dowel-bearing strength is a key parameter for characterizing the local bearing response. This study reviewed the manufacturing processes of laminated bamboo and bamboo scrimber and summarized common testing methods for evaluating the dowel-bearing strength of engineered bamboo products. After introducing the failure modes of dowel-bearing test specimens, the primary influencing factors for dowel-bearing strength were discussed. Based on a database of 1634 half-hole specimens, dowel-bearing strength was predicted using a data-driven machine learning (ML) approach. A new theoretical model based on stress dispersion theory was developed, considering specimen dimensions, dowel diameter, and the corresponding material yield strength in compression. The coefficients in the developed theoretical model were determined using a combined algorithm in which the model was embedded into ML algorithms. It was found that, for specimens loaded parallel and perpendicular to the grain, the dowel significantly influenced a region extending up to 4.50 times its diameter along the corresponding dispersion angle; for specimens loaded parallel to the grain, within the theoretical region of significant influence described above, the dowel also significantly affected a region within 0.45 times the specimen length along the corresponding dispersion angle. The predictive performance of the proposed theoretical model was slightly lower than that of most of the data-driven ML models, but it markedly outperformed the models adopted in current design codes and offered good physical interpretability.