Experimental and theoretical investigation of steel-reinforced bamboo scrimber beams

A novel steel-reinforced bamboo scrimber beam is proposed in which steel bars or prestressed steel bars are embedded in a bamboo composite material. The flexural performance of the reinforced bamboo beam with different reinforcement ratios and different levels of prestressing forces was investigated by a four-point bending test. The results show that both reinforced beams and prestressed reinforced beams fail due to rupturing of the bottom tensile bamboo fibers; no significant yielding failure occurs in the top compression zone. The ultimate bearing capacity of the reinforced beams increases with an increasing reinforcement ratio and prestressing, and the influence of the prestressing is inferior to that of the diameter of the reinforced bars. The flexural stiffness at the serviceability limit state of the reinforced beams increases linearly with an increasing reinforcement ratio and can be enhanced by up to 36.80% compared with that of control beams. The prestressing reinforcement has an insignificant influence on the initial flexural rigidity of the bamboo scrimber beams but accommodates effective upper reverse bending deflection for reducing the actual bending displacement. The calculation methods for the flexural rigidity and bearing capacity are presented by considering the cross-sectional strain and stress distribution of the reinforced beams, and the proposed models are found to provide accurate predictions for both reinforced and prestressed reinforced bamboo beams. Steel-reinforced bamboo scrimber beams can thus be used for long-span, heavy-load bamboo structural engineering.