18th International Conference on Non-conventional Materials and Technologies NOCMAT 2022. Access >>
M. Seixas; S. Paciornik; D. Cardoso; L.E. Moreira
Abstract: Ultralight bamboo structures with flexible joints comprise a novel construction system that can meet the global demand for sustainable buildings, such as multi-use pavilions and temporary structures for disaster relief and humanitarian purposes. In this work, modular self-supporting space frames were designed, fabricated, and experimentally analyzed using bamboo culms, textile ropes, and biocomposite rings. Numerical models and a 1:3 scale prototype were used to investigate the structural response under sustained loadings. The mean values of 5.4 GPa for Young's modulus (E), a specific gravity (G) of 8 kN/m³ , and a Poisson's coefficient (ν) of 0.3 were adopted for the bamboo members. The prototype, constructed with two modular space frames, was tested under both symmetric and asymmetric loading conditions during 43-day static tests. A pronounced nonlinear behavior was observed for the symmetric loading of 4.8 kN and the asymmetric loading of 3.5 kN, whereas failure occurred at a total load of 6.5 kN for the asymmetric configuration, 7.5 times the prototype's self-weight. The observed failure of bamboo members was governed by crushing under bending, followed by local buckling of the upper rafters below the load application points. The experimental results were compared with numerical models to determine an effective modeling strategy for reproducing the actual structural behavior. A comparison revealed that the eccentricity of members at the joints must be considered for a reliable prediction and that creep can be accounted for through appropriate reductions in the modulus of elasticity. The observed differences are attributed to the sliding of members at joints under higher loads and due to local second-order effects. This study investigates the Phyllostachys aurea bamboo mesostructure through optical microscopy and digital image processing. Specimens were produced using a bamboo full-culm with cross-sections sliced from 1, 4, and 6 meters distant from the ground. Digital images captured through light microscopy with the magnification of 200x were digitally processed for the segmentation of sclerenchyma, vessels, parenchyma, and epidermis phases, allowing for the extraction of the material’s anatomical features. Binary images obtained from each phase were produced and, then, measured, showing portions of the constituent phases of P. aurea cross-sections at the bottom, middle, and top parts of the culm, respectively.
