Performance of Nail-Laminated Timber assembled with Wood-Based Fasteners

The use of Nail-Laminated Timber (NLT) as a planar element in building construction has been a code-recognized approach in North America for decades. In practice, the design of these elements is often governed by vibration (deflection) criteria. “Mechanically Laminated Decking”, as NLT is referred to by the International Building Code, has defined sizes and spacings for the assembly of these elements with steel-based fasteners. However, steel-based fasteners limit the opportunity for industrialized customization of these panels during off-site manufacture. Further, steel-based fasteners limit the adaptability for future re-use of the panels in other structures. For these reasons, NLT panels using bio-based fasteners were assembled and tested for stiffness in out-of-plane bending and compared to conventional NLT performance. A Beam on Elastic Foundation model was developed for analytical modeling, experimental testing was performed, and numerical (finite element) modeling was completed. Results showed that the bio-based NLT exhibits 3.9% lower stiffness in experimental testing, and 12.2% lower stiffness in numerical modeling than the conventional NLT. Based on these results, it appears that the substitution of these bio-based fasteners for code-approved steel fasteners in building code approaches for NLT should result in similar performance for stiffness considerations.