Buckling behavior of multi-slat bamboo structural members

Bamboo multi-slat members assembled from longitudinally cut slats offer improved geometric regularity and crack control compared with bamboo culms, enabling their use as load-bearing elements while reducing material waste. This study experimentally and analytically investigates the compressive behavior of bamboo multi-slat members intended for applications such as trusses, frames, and other structural systems. Two assembly approaches were evaluated: (i) planed Guadua angustifolia slats connected with tightened steel bolts, and (ii) naturally curved Dendrocalamus asper slats connected using non-tightened bolts or bamboo pins. The experimental program assessed buckling performance as a function of assembly approach, connector spacing, and connector type. The degree of structural interaction between slats was quantified using an index ratio, where values approaching unity indicate apparent flexural stiffness close to that of a fully interacting cross-section. All specimens failed by elastic buckling without significant material damage. Members assembled with planed slats and tightened bolts developed high index ratios (0.82–1.00), whereas members assembled with naturally curved slats exhibited substantially lower values (0.03–0.38). Increasing connector spacing from 100 to 300 mm reduced the buckling capacity of the first assembly approach by approximately 11%, while a more pronounced reduction was observed for the second approach. For the naturally curved assemblies, non-tightened steel bolts increased buckling capacity by a factor of 1.9–2.6 compared with bamboo pins. The European buckling formulation (EN 1995-1-1) provided reasonable predictions of the average experimental response of members assembled with planed slats when an imperfection factor of 0.39 was adopted but overestimated the capacity of the naturally curved assemblies. Finite element models reproduced the experimental trends and provided reasonable predictions of both buckling capacity and index ratio. The results demonstrate substantial differences in performance between the investigated assembly approaches and indicate that multi-slat bamboo members fabricated with planed slats and tightened bolts represent a promising alternative for compression-dominated structural applications, provided that adequate fabrication quality and connector detailing are maintained.