Journal of the International Association for Shell and Spatial Structure Vol. 57 No. 3, 2016. Access >>
M.A. Seixas; J.L.M. Ripper; K. Ghavami
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 article presents a new typology to build deployable pavilions based on a mobile self-stabilizing bamboo structure. The architecture is characterized by lightweight space trusses of treated bamboo poles covered with a bio-composite made of cotton fabrics, clay, PVA glue and castor oil polymer. The connections of the deployable structure were developed using textile moorings, that minimized efforts on the assembly of the structural members. The roof consists of bamboo pantograph gridshells covered by tensioned PVC canvas. The assembling procedure employs prefabricated structural modules prepared on the floor of the building site and then lifted manually by a set of projected elevators. The method presents a simplified mounting and dismantling process of the structure. The proposed bamboo structure presents an easy adaptability without the need of a specific construction site for its assembly and needs only a mounting area. The mobility of the pavilion, the manufacturing techniques and the natural materials favored the design of new forms for construction, with clean use of local spaces. These considerations resulted in an agile execution with minimum waste, in addition to low energy consumption and low environmental impact for the production of the structure.
