Experimental Investigation of Net-Tension Capacity in Birch Plywood Gusset Plates via Mechanical Connectors and Adhesives

Abstract: This thesis examines the mechanical behavior and performance of plywood connections withmechanical connectors and adhesive bonding to glulam. The aim is to provide insights into thecapacity and characteristics of these connections for well-founded design decisions in timberstructures.Through a comprehensive literature review, the existing knowledge on plywood-glulamconnections and mechanical connectors is explored. Joint configurations, material properties,and testing methods are analyzed to establish a foundation for the experimental investigation.Experimental tests are conducted on plywood specimens connected with mechanical dowels atdifferent angles to the face grain. The net-tension capacity of birch plywood is evaluated byvarying specimen width. The results reveal a capacity plateau at specific widths, indicatingoptimal connection performance. However, further tests are needed to determine the precisecharacteristics of the plateau, especially for wider widths uncommon in practical applications.Analytical predictions are also employed to estimate connection performance. A spreading angleof 11 degrees yields the closest match to experimental results, showcasing the effectiveness ofthe analytical approach. However, deviations are observed, attributed to factors like local fiberdeviations and potential human error. Further investigations are recommended to enhance thereliability of the analytical model.The thesis also investigates the connection between plywood and glulam via adhesive, tests atdifferent angles yield intriguing results, including a sudden capacity drop at a specific width forzero-degree connections. Surprising phenomena are observed, such as the contrasting behaviorof narrower and wider widths in 0-degree and 22.5-degree specimens. Further research iswarranted to understand these phenomena and design plywood gusset plates with consistentcapacity across all angles.Analytical predictions for adhesive-bonded connections are limited due to the absence of acapacity plateau. Nonetheless, a spreading angle of 5 degrees is identified as the closestprediction to test results, demonstrating the potential of the analytical approach. Deviationsbetween predicted and observed capacities are acknowledged, underscoring the need for furtherinvestigations and consideration of parameters like adhesive types, plywood properties, andalternative joint configurations.In conclusion, this thesis provides valuable insights into the behavior and performance ofplywood connections with mechanical connectors and adhesive bonding to glulam. Theexperimental and analytical findings contribute to the existing knowledge base and offerpractical implications for the design and implementation of these connections in timberstructures. Future research can build upon these findings to advance the understanding anddesign of plywood-glulam connections.