Experimental and nonlinear analytical investigation of the flexural performance of single-box double-chamber steel–bamboo composite beams

Steel–bamboo composite structures present excellent and stable engineering performance. This study presents a novel single-box double-chamber steel–bamboo composite beam consisting of cold-formed thin-walled steel and bamboo scrimber. Nine single-box double-chamber steel–bamboo composite beams were prepared with various section parameters. A four-point bending test was conducted to evaluate the flexural behaviour of the beams. The failure mode, deflection deformation, and load-carrying capacity were analysed based on the test phenomena and data; the influences of the various parameters on the flexural behaviour were explored. Finally, nonlinear analytical models were developed considering the nonlinear constitutive law of beams and the influence of the steel–bamboo interface slip. The results indicated that lateral instability and local buckling behaviours were effectively avoided, and two failure modes were identified. The bending resistance was improved by reducing the flange bamboo width–thickness ratio, steel height-thickness ratio, and increasing the height of the web. The bending capacity depended more on the bamboo than that on steel. The nonlinear analytical models provided accurate predictions for the beams with tensile failure. Discrepancies between the experimental and analytical results were less than 8.6%.