Experimental study on flexural behavior of glulam and laminated veneer lumber beams

Poplar is one of the main fast-growing species in China. In this study, the Italian poplar is used in the manufacturing of engineered wood materials, such as glued laminated timber (glulam), laminated veneer lumber (LVL), etc. The overall objective is to take full advantage of the fast-growing species in China and make it applicable to modern timber structures. Firstly, through a series of material mechanical testing, the main physical and mechanical behavior of glulam and LVL were presented. Based on this, experimental study on a total of 31 engineered wood beams was developed and the failure modes and failure mechanism were analyzed in this paper. Then the flexural behaviors, which include load carrying capacity and bending stiffness, were investigated and made a detailed comparison among them. Finally, the influences of lamination combination, load direction, veneer thickness (for LVL members), and beam sizes upon the flexural behaviors of engineered wood beams were discussed. Experimental results have shown that structural behaviors of engineered wood beams were much better than those of sawn beams made from ordinary structural timber. For example, the ultimate load of poplar engineered wood beams exceeds that of sawn Mongolian Scotch pine (MSP) beams by 39.0%similar to 90.0%, while bending stiffness increased by 35.0%similar to 45.0%. When combining LVL with glulam in the beams, they would produce better structural performance. Also the average strain of beam cross-section showed a linear distribution, and the ultimate tensile strain of the beams is 0.006 while the maximum compressive strain of the beams is about 0.009. Moreover, the influences of lamination combination and beam sizes on the beam's flexural behavior are obvious. From this study, it shows that engineered wood materials have a good prospect in building structures of China.