Cross-Laminated Timber (CLT) is a prefabricated building material that is relatively new to the United States and North America. It consists of no less than three layers of graded, dimensional lumber glued in alternating longitudinal and transverse layers to create a panel that can be used for various building applications (walls, floors, etc.). Panels are always constructed in an odd number of layers with the two outer layers oriented longitudinally.
Currently, building codes in the United States do not have an abundance of information on CLT construction. Accurately predicting behavior of panels and connections is imperative for static and dynamic analysis of structures that use this new material. Current information about CLT connections is based primarily on physical test data and visual observations of those tests. Creating computer models of the connections can provide more insight into their structural behavior and possibly ways to improve upon the designs. The models can be used to examine various changes in connection geometry and material properties to complement physical testing of some of those variables. The methodology outlined in this project is general enough to be applied to many different types of nailed CLT bracket connections.
A single, laterally-loaded nail embedded in Douglas-fir is tested and used to confirm a Finite Element Analysis (FEA) model using ABAQUS and Material Point Method model (MPM) using NairnMPM. The single nail model serves as a simple and efficient way to test and troubleshoot methods of modeling a connection. It also serves as an actual subset of the connection. Being a smaller model than a full connection, results can be calculated and extracted faster. The same methods used to develop the single nail model are used to construct a full connection model once confidence in the single nail model is gained. The model is used to analyze the stress contours and locations of material damage of connections used to fasten CLT walls and diaphragms together. Results from the single nail connection model are encouraging, while the results of the full connection model need further refinement. Recommendations for current applications of connection models are discussed along with recommendations for future work and necessary improvements. Commercial FEA software such as ABAQUS do not have the capabilities to model complex wood connections without the use of user- defined features.