An experimental study on the structural stability and buckling behaviour of slender bamboo culms

The structural stability of axially compressed members is essential for the design of safe and efficient load-bearing systems. Within sustainable construction, bamboo has emerged as a promising renewable building material due to its high specific strength and low environmental impact. However, due to its natural anisotropy and geometric variability, the buckling behaviour of bamboo differs significantly from that of conventional isotropic materials. This study presents experimental investigations of flexural buckling in full-scale bamboo culms with intermediate and high slenderness ratios. After a concise review of theoretical approaches for predicting buckling capacities, the experimental methodology of the present study is described, including specimen preparations, test setups, and boundary conditions of the experimental studies. The experimental results are then analysed to assess load-displacement behaviour, the influence of initial imperfections, and correlations between material as well as geometric parameters and the flexural buckling capacities. Finally, existing methods for recalculating flexural buckling capacities, as well as the design method for axially loaded bamboo culms based on ISO 22156 are evaluated against the experimental results. The analysis indicates that ISO 22156 leads to overly conservative capacity estimates, failing to adequately reflect the load-bearing performance of long, slender bamboo culms and demonstrating a significant variation in safety margins across different slendernesses. The findings of this study highlight the need to revise current design methods to ensure the safe use of bamboo as a structural material and to strengthen engineers’ confidence in its use.