Effect of Interlocked Laminates on Fracture of Laminated Veneer Lumber in Dowel-Bearing Strength Test
Koji MURATA, Hiroshi KOYABU and Takato NAKANO
Abstract:Using the longitudinal and flexural vibration method, the Youngfs modulus and shear modulus of the interlocked laminated veneer lumber (LVL) with symmetric angle-ply laminates were measured by tapping; in addition, the connection strength was tested with a drift pin. The measured mechanical properties of the interlocked LVL were consistent with those predicted by the so-called classical lamination theory; further, it was found that the properties change to a great extent with the interlock angle (orientation angle of veneer) but do not vary with small changes in the interlock angle. The connection strength of the interlocked LVL was determined by a dowel bearing strength test (embedment strength test). The dowel bearing strength tended to decrease to a small extent with an increase in the interlock angle. While the Youngfs modulus decreased to a great extent for changes in the interlock angle exceeding 10 degrees, the initial stiffness obtained from the embedment stress-displacement curve decreased to a small extent with the interlock angle. The analysis of the curve after the yield point revealed that the stress increased (strain hardening) when the interlock angle was greater than 10 degrees. The connection properties tested with a drift pin depend on not only the Youngfs modulus of the main member but also its shear modulus; further, the angle-ply laminates prevent the member from cracking due to its expansion after yielding. Key Words:Interlocked LVL, Symmetric angle-ply laminates, Dowel bearing strength, Youngfs modulus, Shear modulus