Sustainability in the Built Environment – Evaluating Spline Connections in Eastern Hemlock Cross Laminated Timber

Wood buildings provide healthy indoor environments, energy efficient building design, low-carbon and resource efficient technologies, and many other benefits to the built environment. My project aims to foster the use of cross laminated timber (CLT), an engineered wood panel used in the construction of large-scale buildings and made from adhering dimensional lumber in a layered, crosswise manner. Eastern Hemlock (Tsuga Canadensis) lumber was chosen because this tree species is abundant in New England yet underutilized as a forest product, and thus a good candidate for local production of CLT. The goal of my project is to quantify monotonic and cyclic behavior of panel to panel assemblies of single surface splines (e.g. strips of lumber): (i) with adhesive and (ii) without adhesive. I hypothesize that the panel to panel assemblies that have adhesive will perform stronger and stiffer because including adhesive in the connection will increase shear resistance and improve the overall connection ability to resist loads. A specimen consists of three Eastern Hemlock CLT panels with two single surface splines and four screws connecting them. The specimens were fabricated using standard shop tools: a chop saw, a band saw, a drill, and others. Laminated veneer lumber panels were attached to steel rods that held down the specimen while the head of the MTS testing machine was attached to the top of the specimen. This allowed for static and cyclic loading. Yield and deformation data were collected. It was found that the glued specimens performed stronger and stiffer but responded with more variability than the non-glued specimens.