Effects of Re-drying on properties of cross laminated timber (CLT) connections

As mass timber buildings continue to gain widespread acceptance in North America, there is the need to address concerns, which might impact the performance of these novel buildings. Moisture intrusion poses significant levels of risks to mass timber elements and has been associated with durability concerns and possible reduction in performance of structural elements and connection systems. While it is recommended to employ design approaches that eliminate moisture accumulation in buildings, the possibility of elements getting wet during, or post construction remains reasonably high. Hence, it is important to re-dry elements once wet to avoid these issues. Additionally, connections constitute an important part of the lateral force resisting system and must be well studied for optimum performance under all conditions. This study therefore characterized the wetting and redrying performance of Cross Laminated Timber (CLT) angle bracket connections made from four CLT species. The effects of three different drying methods on the load carrying capacity, stiffness, and energy dissipating capacity of the connections were studied. Load carrying capacity of the connections was barely affected, but aggressive drying induced brittleness in some connections, and consequently impacted energy dissipating capacity. Physical observation of the connection assemblies also showed varying degrees of damage, which can be attributed to accumulation of drying stresses depending on the drying method employed.