Supplementary information files for "Experimental investigation of the moisture-dependent behaviour of Norway spruce glulam beams"

Supplementary files for article "Experimental investigation of the moisture-dependent behaviour of Norway spruce glulam beams"<br><br>This study presents an experimental investigation into the influence of moisture content (MC) on the structural behaviour of Norway spruce glued-laminated (glulam) timber. The moisture-dependent material properties were first quantified through a series of auxiliary tests on clear timber samples in compression and tension, both parallel and perpendicular to the grain. A total of 26 glulam beam specimens were subsequently tested under three-point bending (TPB) and four-point bending (FPB) configurations to assess flexural and shear performance under varying MC. Specimens were conditioned to six distinct MC levels (5%-30%) under controlled environmental conditions. The results showed that increasing MC from dry conditions to the Fibre Saturation Point (FSP) at 30% led to reductions in compressive and tensile strength of over 50% and 30%, respectively, in both the parallel and perpendicular directions. Beam testing over the same MC range (from 5% to 30%) revealed reductions of up to 31% in flexural and shear strength values, while flexural stiffness declined by 58%. Failure modes transitioned from brittle flexural rupture at low MC to more ductile mechanisms, such as shear cracking, crushing, and interlaminar delamination, at higher MC. The results were then used to evaluate the characteristic strength prescribed by Eurocode 5, which remained conservative across all MCs. However, the uniform treatment of service classes SC1 and SC2 may underestimate strength losses at intermediate MC levels. Evaluation of the test data in the shear–bending interaction space further confirmed the conservative nature of the simplified linear interaction equation.<br><br>© The Authors, CC BY 4.0