Experimental research on flexural performance of dowel laminated timber composed of LVL made from fast-growing larch

Based on the dowel laminate timber production method and the laminated veneer lumber (LVL) material characteristic, a new type of mass timber, known as dowel laminated veneer lumber (DLVL), was developed using small-thickness LVL made from fast-growing larch (Larix gmelinii Rupr), which could be made into beams with large cross-sections. Four-point bending tests were carried out on DLVL beams. The flexural performance of vertical DLVL (V-DLVL) and horizontal DLVL (H-DLVL) beams was compared. The impacts of lamina thickness and width on the flexural strength and effective flexural stiffness of H-DLVL beams were further investigated. The prediction formulas of the flexural capacity and effective flexural stiffness of H-DLVL beams were proposed. The results showed that the flexural strength and effective flexural stiffness of H-DLVL beams were about 2 and 8 times that of V-DLVL beams with the same cross-section, respectively. The flexural performance of H-DLVL beams made from fast-growing wood was comparable with that of other engineered wood beams. The lamina thickness combination affected the flexural performance of H-DLVL beams. When the beam cross-section was constant, the flexural strength of H-DLVL beams composed of 20 mm and 40 mm mixed thickness LVL laminae was a little higher than that of H-DLVL beams only composed of 20 mm or 40 mm thickness LVL laminae. The prediction formulas considering the size effect could successfully predict the flexural capacity, maximum deflection, and effective flexural stiffness of H-DLVL beams.