Experimental Study On Bamboo-Wood Material Selection Of Prestressed Glulam Bamboo- Wood Beam

The timber resource was increasingly nervous in the worldwide, the bamboo was the only generally acknowledged green material that can replace timber resource at present. Bamboo-wood composite material was composite board or joist lumber, which was combined and adhesive bonded by bamboo or timber or the same or different structural unit, bamboo-wood composite material was used in the present timber structure, it can greatly improve the added value of bamboo-wood composite material. Bamboo timber beam was the main stressed member in modern timber structure building, but the deficiencies of some aspects were bad for the popularization of bamboo timber beam, which were the material selection incomplete of bamboo-wood composite material and using of stiffness control in carrying capacity ultimate state design and the brittle broken failure characteristics of specimen, For the reason, the research work carried out in this paper was listed as follows:To give full play to the compressive strength of glued bamboo wood composite material, a type of prestressed glued bamboo timber beam was built by using the screw thread twist tension transverse tension device, which was suitable for the type of presressed glued bamboo timber beam; To avoid the influence of end local pressure on measurement results when compression test was conducted on test block, the glued bamboo-wood composite material test block with the size of I OOmm×100mm×300mm was made.By the bending tests of 4 batched 22 groups (in all:132) glued bamboo-wood composite material test block, the influence of the glued bamboo-wood composite material parallel to grain compression performance on single material type, different composition pattern, layer plate thickness, lamina lay-ups type were researched. Research showed that, the failure mode of glued bamboo-wood composite material test block were mainly end local pressure failure,laminates buckling and laminates tackless failure, the compressive strength had a greater improvement than glue-lumber specimen after composited, the elastic modulus of the two was close, which made them have the feasibility to work together. The compression performance of specimen combined with reconsolidated bamboo and timber was better, to avoid the happening of cemented surface cracking failure, the layer plate thickness should increase and the effect of interval layout was the best, the compressive elastic modulus of test block combined with northeast larch,eucalyptus and reconsolidated bamboo was higher, the compressive strength of test block combined with northeast larch,poplar and reconsolidated bamboo was greater. The above research achievements can provide material selection reference for the production of prestressed glued bamboo-timber beam.By the bending tests of 7 roots prestressed glued bamboo-wood beam, the influence of the glued bamboo-wood beam bending performance on different composition pattern and lamina lay-ups type from material selection level were further researched. The results showed that, the ultimate carrying capacity of specimen with bamboo timber interval layout increased 15.84%-23.23% than bamboo on both sides, increased 10.61%-76.76% than bamboo on one side; It had the higher flexural rigidity when northeast larch and reconsolidated bamboo arranged interval, and it had the higher carrying capacity when poplar and reconsolidated bamboo arranged interval. Considering the disadvantage of laminates unease adhesion between northeast larch and reconsolidated bamboo and after comprehensive analysis, it is suggested that poplar and reconsolidated bamboo interval layout with the layer plate thickness of 20mm was selected as the material selection scheme of prestressed glued bamboo-timber beam.