Flexural experiments on prestressed glued bamboo and lumber beam for material selection

摘要

This paper attempts to lay down a material selection criterion for prestressed glued bamboo and lumber (GB&L) beam and other components using bamboo-lumber composite as the main compression member. Through flexural experiments on nine prestressed GB&L beams, the author explored the effects of material type and composite pattern on flexural behaviours, and analysed the performance indices like ultimate bearing capacity and ultimate displacement. The main conclusions are as follows: The typical failure mode of the GB&L beam includes the compressive buckling failure atop the beam at the trisection points, the tensile failure at the bottom, and the horizontal tearing failure. The ultimate load of bamboo and lumber beam was 36%~56% higher than that of poplar beam. Among the GB&L beams, the alternatively arranged section specimen enjoyed the best strength, the compression strain atop the beam fell between 8,000 and 16,000, and the tensile strain at the bottom ranged from 4,000 to 12,000. The strains were much better than those of glued lumber beams, and comparable to those of reconsolidated bamboo beams. Throughout the loading process, the compressive zone was always larger than the tensile zone, and the compressive strain was more obvious than the tensile strain, indicating the full utilization of compressive strength in GB&L beams. The findings of this paper lay the basis for the material selection of prestressed GB&L beam and other compressive components.