Structural performance of timber rivets in engineered wood products

Abstract

Timber Rivets are oval-shaped nails made from high-strength steel that allow for strong and ductile timber connections. Timber Rivets have been successfully used in the construction industry for over 40 years. Both the Canadian design code (CSA-O86) and the American design code (NDS), however, only specify Timber Rivets to be used with Glulam and solid sawn timber of certain species. In recent years, significant research has been conducted in New Zealand regarding the application of Timber Rivets to Laminated Veneer Lumber. As a result, the Johansen Yield Model, which is verified as a valid approach to predict the ductile failure of Timber Rivet connections, has been complemented with new failure models and design equations that predict brittle failure modes. The objective of the research was to evaluate the feasibility of using the novel models to predict the failure modes and capacities of Timber Rivet connections in Laminated Veneer Lumber and Cross Laminated Timber. The experimental investigations carried out as part of this thesis consisted of 29 test series (with three or five replicates each) of Timber Rivet connections in these structural composites made from North American species. Quasi-static monotonic and cyclic tests with loading parallel and perpendicular to the grain were conducted in the Wood Mechanics Laboratory at the University of British Columbia Vancouver. The quasi static tests were used to validate the prediction models; the cyclic tests were used to assess the seismic performance of the connections. The results showed that the recent New Zealand model provides good predictions for Timber Rivet connections in Laminated Veneer Lumber. Furthermore, it was shown that cyclic loading does not severely weaken the performance of Timber Rivet connections. The existing models, however, do not provide accurate predictions for Timber Rivet connections in Cross Laminated Timber and more research is deemed necessary before such connections can be safely designed.