Flexural behavior of hybrid composite beams with a bamboo layer and lattice ribs

This paper presents an experimental investigation of flexural behavior of hybrid composite beams with glass fiber reinforced plastics box skins, a polyurethane foam core, a bamboo layer, and lattice ribs. The bamboo layer was placed on the top of a wrapped polyurethane foam core. The lattice ribs were distributed along the longitudinal direction of the beam. Four beams, involving a control specimen, were loaded in four-point bending to validate the effectiveness of the bamboo layer and lattice ribs for increasing the ultimate bending strength of the hybrid composite beams. Compared to the control specimen, a maximum of an approximately 85% increase in the ultimate bending strength can be achieved. The beam with bamboo layer reinforcement and without lattice ribs exhibits the highest stiffness-to-weight ratio, while the beam with both bamboo layer and lattice ribs exhibits the highest strength-to-weight ratio. Meanwhile, various failure modes were summarized, including compressive and crushing failures. Finally, an analytical model to predict the bending stiffness and ultimate bending strength of the hybrid composite beams was proposed. Furthermore, the analytical results were agreed well with test results.