Testing and analysis of screw-connected moment joints consisting of glued-laminated timbers and birch plywood plates

Abstract

This study presents the feasibility of constructing moment joints using birch plywood plates and glulam beams. Beam-beam joints consisting of birch plywood gussets and glulam beams connected by self-tapping screws were built and tested in the four-point bending regime. Analytical calculations based on the fastener group’s torsional moment resistance, the proposed elastic and post-elastic fastener group’s load-bearing criteria, and the design formulas given in Eurocode 5, are performed to predict the connection capacity in both elastic and post-elastic stages. Under the four-point bending, all specimens with birch plywood plates with the face-grain orientation of either 0° or 22.5° to the beam length direction, showed brittle failure either in the glulam beam or birch plywood plate. Numerical models are constructed to capture the global load–deflection behavior of all beam specimens. The foundation zone modeling scheme is adopted to consider the influence of the fasteners’ embedment on the macroscopic load–deflection curves. As a result of comparison, the analytical calculations give reasonable predictions on both the elastic and post-elastic ultimate beam capacity, and the numerical models give satisfactory predictions on the bending stiffness for all tested beam specimens.