Construction panels made with pre-stressed wave layered timber

Stress laminated timber (SLT) is a construction system created by compressing multiple layers of timber together with pre-stressed steel tendons. SLT has the advantage of being adhesive free, constructable on-site, and deconstructable after use. In the present study wave layered timber (WLT) is investigated, which is an altered version SLT which aims to utilize timber boards with a wave-shape cut into them to enhance performance.
Information on the performance of STL is present in the literature, with practical importance on timbe bridges, e.g., Ritter (1990), Crocetti et al. (2016), Massaro and Malo (2020). WLT on the other hand is a rather new system with little scientific background detailing it’s physical and mechanical performance. There are some construction projects already utilizing WLT (e.g., in Finland), however, studies investigating the design parameters for such systems are lacking and the performance under different service conditions are not well reported. Since the wave shape offers a different type of connection between the adjacent layers, compared to the flat planed timber used in SLT, the system behaves differently than conventional SLT. It is therefore important to understand the behaviour of WLT prestressed construction panels and their potential advantages.
Important to stress laminated systems is the fact that timber is inherently susceptible to moisture leading to swelling and shrinkage and changes in the stress state of the system. In addition, the time dependency of wood influences stressed systems, since over time, wood relaxes from the initial stressed state to one of lower stress when a permanent deformation is applied. In the present study, experimental investigations are conducted to examine how WLT behaves under varying relative humidity conditions and during relaxation.