Influence of Freezing and Thawing on the Structural Behaviour of Laminated Veneer Lumber Beams

Laminated veneer lumber (LVL) is an engineered structural composite lumber that is used in structural framing applications in residential and commercial construction. Because LVL is commonly used as structural members in applications that could be exposed to moisture and freeze–thaw cycles, there is a need to better understand the behaviour of the material under harsh environmental conditions, including studying the influence of freezing–thaw cycling on its bending strength. To address this need, this paper presents experimental results on the structural performance of four large-scale LVL beams tested in dry conditions as well as after being subjected to freeze–thaw cycles over a period of two weeks. The 3.25 m long beams were tested under four-point loading to evaluate their bending strength, stiffness, and failure mode. The beams were also instrumented with distributed fibre optic sensors to evaluate the strain distributions along the length of the beams. Experimental results demonstrate that the freeze–thaw cycles had little-to-no effect on the structural capacity of the LVL beams. Distributed fibre optic sensors were found to be an effective approach for capturing the complete strain distributions along the length of the beams and could be used to identify structural defects in the timber as well as to measure the beam curvature throughout the experiments. Overall, results of this study demonstrate the effectiveness of LVL in situations in which it could be exposed to freeze–thaw cycles.