An Experimental and Numerical Investigation of the In-plane Shear Behavior of Cantilever Cross-Laminated Timber Diaphragms

This research focuses on investigating the behavior of Cross Laminated Timber (CLT) diaphragms under in-plane shear loads through an experimental, analytical, and numerical approach. Full-scale destructive tests were conducted on cantilever CLT diaphragms to measure their response to cyclic loading. The results showed that the ultimate capacity of the diaphragms was primarily influenced by the fasteners used and exceeded the LRFD capacity. The primary energy dissipation mechanism was through the slip of diaphragm components and rotation of CLT panels due to fastener deformations. The strain data revealed that the diaphragms exhibited deep-beam-like behavior, with resistance to tensile and compressive forces primarily contributed by the outer edge panels. A design procedure for tension and compression chords was proposed based on the strain data. Additionally, the analytical equation for CLT shear walls was modified to predict deflections in cantilever CLT diaphragms, and the findings were validated through full-scale tests. The repairability of damaged CLT diaphragms was also investigated, and it was found that repair using new fasteners could be a viable option for performance restoration. Lastly, numerical models were developed and validated using experimental data and extrapolated to predict the behavior of other diaphragm layouts, spans, and configurations. Overall, this study provides insights into the behavior of CLT diaphragms under in-plane shear loads and offers recommendations for their design. The findings will be helpful for designers and engineers in the construction industry interested in using CLT as a diaphragm material. Further testing is recommended for different failure scenarios and fastener configurations