Development of a glue bonded shear connections aimed for mass timber composites

Mass timber composites (MTCs) generally require stiff glued connections to meet serviceability design criteria; however, achieving stiff glued connections without conventional pressing infrastructure can necessitate alternative gap filling adhesives. A readily available construction adhesive with potential for use with alternative pressing methods is investigated to develop the needed information for its commercial application in MTCs. The glue line thickness, surface coverage, three contact pressures, and how these parameters influence the load-slip curve of the connection when loaded in pure shear are investigated. The average glue line thickness ranged from 0.76 to 0.33 mm, with lower pressures having thicker glue lines and higher pressures having thinner glue lines. The planning precision was found to be more critical than clamping pressure for glue line thickness. Based on glue bond thickness testing and fabrication experience it is recommended to use 1.2–1.4 mm 2 of adhesive per mm width to create full coverage glue bonds without excessive adhesive squeeze out. When tested under pure shear, specimens were observed to fail with a mixture of wood and glue, with more glue failure present as the pressure was increased. The initial stiffness of the connection tended to increase with clamping pressure, while the strength tended to decrease. Two bi-linear data fit models are applied to determine the yield point and simplify the load-slip behaviour for use in design analysis. Overall, the 75% max load method better fit the behaviour and was simpler to apply. The shear strength and stiffness achieved experimentally across all pressures were comparable to other glue connection literature results, and when applied in the design of a 10 m long MTC ribbed panel all pressures achieved near fully composite action. Overall, the adhesive has shown to be an easy to apply and structurally viable connection alternative for MTCs.