Glued-in steel plate connections in glulam: Mechanical behaviour and joint performance

This paper presents a comprehensive experimental and analytical investigation into the mechanical behaviour of glued-in steel plate connections in glulam structures. Pull-pull tests on connection specimens demonstrated that the surface preparation of steel plates is a critical factor. Chemical etching proved to be the most effective method, as it removed the weak oxide layer and enabled ductile failure through steel yielding. The load-bearing capacity increased with anchorage length and width up to certain thresholds, beyond which the rate of improvement diminished, attributed to the non-uniform distribution of shear stresses. An empirical model was developed to predict load-carrying capacity, showing good agreement with experimental results. In addition, the rotational performance of the proposed beam-to-hub joint incorporating glued-in steel plate connections was evaluated under combined axial compression (0, 250, and 500 kN) and bending. Increased axial compression shifted the failure mode from tension-side plate pull-out to compression-side timber shear fracture, and generally enhanced both initial stiffness and moment capacity. However, this beneficial effect diminished when axial compression reached high levels. The inclusion of backup bolts provided an effective fail-proof mechanism, ensuring reasonable post-peak ductility. The ultimate bending capacity predicted by the proposed equilibrium equations aligned well with the experimental data, validating the model as a reliable tool for joint design.