PSI - Issue 78

Martina Sciomenta et al. / Procedia Structural Integrity 78 (2026) 253–260

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in hybrid configuration is 12.66% lower than the one in glulam beech configuration, contrarily, on chestnut their ductility increases of 15.28%. For VGS9x160 with a 40 mm side board (Fig.3) the hybrid beech-Silver fir configuration achieves the highest ultimate force max ' F , compared to glulam beech is less than 2.83% the glulam chestnut series is also smaller but of a much higher value equal to 43.47%. In terms of slip modulus, s K , the screws in hybrid configuration were characterized slightly higher stiffness equal to 5.72% than these in glulam beech configuration, contrarily, the values achieved with chestnut configuration are 27.87% lower than beech. The ductility of fasteners in hybrid configuration is slightly higher than the one in glulam beech configuration (6.67%), instead on chestnut their ductility increases of 36.19%.

Fig. 3. Comparison of experimental evidence among the series a) VGZ 9x160 with 40 mm board; b) VGS 9x160 with 40 mm board

During the tests, different failure modes were observed: in Series #1, specimens with VGZ screws exhibited the formation of a plastic hinge in the portion embedded in the central element, whereas specimens with VGS screws showed the development of a double plastic hinge; in Series #2, in both configurations, a plastic hinge was formed in the screw segment embedded in the central element; in Series #3, in both configurations, the formation of a double plastic hinge was observed.

Fig. 4. Failure mode: a) Glulam Beech with VGS screws; b) Hybrid with VGZ screws