Experimental study on glulam joints with slotted-in-steel-plate in large-span steel-timber hybrid structures

Glulam joints with slotted-in-steel-plate are widely used in steel-timber hybrid structures due to their aesthetic appeal, simplicity, and efficient load transfer. However, the mechanical performance of these joints is significantly influenced by various factors. This study systematically investigates the effects of five key parameters, including contact conditions, fastener types, number of steel plates, loading protocols, and fastener arrangement on the mechanical behavior of glulam joints with slotted-in-steel-plate. Eight specimens were designed and tested to evaluate their failure modes, load-bearing capacity, stiffness, ductility, and energy dissipation under both monotonic and cyclic loading conditions. The results demonstrate that the five factors bring different effect on the joints. The load transfer mechanisms of the joints with different fasteners play a critical role in determining the influence of the variable settings. The pre-tensioning in bolted connections generates frictional resistance between the connected components, effectively delaying crack propagation and enhancing energy dissipation under both monotonic and cyclic loading conditions. Joints with self-tapping screws (STSs) as fasteners, despite exhibiting higher initial stiffness, are prone to rapid stiffness degradation and brittle failure under cyclic loading due to the absence of preload and the accumulation of damage. The experimental data and analysis serve as a reliable basis for future theoretical studies and provides valuable insights for the design and application.