Study On The Structural Performance Of Laminated Veneer Lumber (LVL) Beams

As a wood-based composites, Laminated Veneer Lumber(LVL) is a high performance alternative building material, which in performance achieves greater strength with smaller weight, stiffness, and mechanics stability from a timber resource than solid lumber. LVL application in public building with a long span is broad in the future. LVL has be abroad used in building and bridge.In dissertation, LVL is made of fir and poplar, the stress-strain for LVL beams is an elastic-plastic in compression, and linear elastic in tension according to its mechanical property experiments and composite materials theory. LVL beams are made of LVL with PF resin together in factory. The flexural experiments on the poplar LVL beams and the fir LVL beams are conducted, including 20 entries poplar LVL beams, 3 entries fir LVL beams and 6 entries wood beams. The failure patterns, bend strength and stiffness of LVL beams are studied, beams volume and wood species influence flexural strength, which is studied according to the flexural experiments, as a result of the flexural experiments on beams, LVL is a high-performance alternative building material, has a large increase in strength and stiffness contrast against wood.The analytical model based on the weakest link theory on brittle materials, and influence factor D, of veneer thickness and influence factor Cy of beams volume are defined by mathematics method. The relation between bend strength and tension strength is given. According to composite materials theory, the formula of rigidity is defined, and the relation between rigidity and the piles number of veneer is analyzed.The LVL beams with loading go through elastic process and elastic -plastic process. The analytical model based on a strain compatibility and the stress-strain relation, and the formula of the limited load is defined. The analysis of the limited load in order to compare the analytical of results with experimental results have been provided. And the study finds that the theoretical equations share a good agreement with experimental results of the tests beams.