Experimental evaluation and theoretical prediction of dowel-type joints connecting laminated veneer lumber with wood dowels

Laminated veneer lumber (LVL) is an engineering wood product made of veneer through laminated grouping and pressurized gluing, and it can efficiently use fast-growing and small-diameter wood. The existing connection methods for LVL structures are mainly metal fasteners. Compared with metal fasteners, wood dowels have the characteristics of being easy to tear down and recyclable, which has gained increasing attention in recent years. Based on this, the proposal suggested a dowel-type timber joint for connecting LVL members or laminates. Bending tests of wood dowels, dowel bearing tests between wood dowel and LVL, and double-shear tests of dowel-type timber joints were carried out. Several factors were analyzed to explore their influence on the failure mechanism and shear capacity of dowel-type timber joints. These factors include the wood grain direction, the ratio of side laminate thickness to dowel diameter, and the thickness ratio of middle-to-side laminate. Simplified models of dowel-type timber joints under main failure modes were established, and a theoretical equation of shear capacity was proposed based on Johansen's theory. The test results showed that the shear capacity of dowel-type timber joints was comparable to that of dowel-type steel joints under the same dowel diameter. The wood grain direction of laminates had little effect on the failure modes of dowel-type timber joints, but it could affect the shear capacity of joints by affecting the dowel-bearing capacity. The parameter analysis showed that the ratio of side laminate thickness to dowel diameter had an important effect on the failure modes of dowel-type timber joints. The failure modes of joints approached shear failure as the ratio increased. The modified theoretical equation could well predict the shear capacity of dowel-type timber joints under plastic hinge failure and shear failure.