1. Long-term durability of flax-glass hybrid FRP-timber composite structures subjected to hygrothermal environment : experimental and simulationSilu Huang, Libo Yan, Bohumil Kasal, Wei Yang, 2025, original scientific article Abstract: This paper focuses on the experimental and numerical analysis of long-term performance of flax-glass hybrid FRP (HFRP)-laminated veneer lumber (LVL) joints and beams subjected to hygrothermal environment (50℃ and 95 %RH) for six months. The joints and beams with different fibre fabric stacking sequences of HFRP exposed at different exposure intervals (0, 1, 2, 3 and 6 months) were tested under block shear and four-point bending, respectively. The tensile properties of epoxy and HFRP composites under those exposure intervals were also examined to explore degradation mechanisms of HFRP in LVL-HFRP beams. Tensile strength and strain of HFRP showed a major reduction (26.7 – 32.1 %) in the first month of exposure. Hydrolysis and oxidation of epoxy were found to have insignificant effects on HFRP tensile properties, based on Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) results. A significant decrease (34.7 – 35.7 %) of LVL-HFRP joints in their shear strength was attributed to weakened hydrogen bonds between cellulose and lignin-hemicellulose matrix, along with the degradation and softening of hemicellulose. LVL-GF beams in which the glass fibre layer of HFRP was adhered to LVL exhibited a major reduction in bending strength (23.4 %) after the first month of exposure. In LVL-FG beams where the flax fibre layer was adhered to LVL, a major decrease in bending strength (25.8 %) was observed after two-month exposure. The postponed reduction in LVL-FG beams compared with LVL-GF beams was caused by the slower moisture diffusion in HFRP of LVL-FG beams than that in LVL-GF beams. A diffusion–stress coupled finite element (FE) model was developed, incorporating moisture diffusion and moisture-dependent mechanical properties for both the timber and HFRP components. Based on this model, the flexural response of LVL–HFRP beams after hygrothermal exposure was simulated, showing satisfactory agreement with experimental results. This research developed a step towards the long-term performance evaluation of HFRP-timber composite structures with different fabric stacking sequences of HFRP.
Keywords: long-term durability, hybrid FRP, timber-hybrid FRP composite structure
Published in RUP: 23.12.2025; Views: 207; Downloads: 2
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2. Experimental and analytical evaluation of shear capacity of reclaimed timber connections with thermo-mechanically densified wooden dowelsMohammad Derikvand, Donya Bazyar Khoshroodi, 2025, original scientific article Abstract: The reuse of reclaimed timber in structural applications is increasingly recognized as a strategy to extend ma- terial life cycles and reduce waste. Particular attention has recently turned to reusing reclaimed timber in adhesive-free laminated products with wooden dowels, where connection performance is critical. The aim of this study was to investigate the mechanical performance of double-shear connections assembled from reclaimed spruce timber using thermo-mechanically densified wooden dowels. The dowels were first evaluated in bending and embedment tests on lamellae made from both reclaimed and virgin spruce timber. The shear capacity of the connections was then evaluated in three layups: two homogeneous (all-reclaimed lamellae and all-virgin spruce lamellae) and one hybrid (reclaimed side lamellae with a central virgin spruce lamella). Analytical predictions were performed based on the draft of the new Eurocode 5, however, with two alternative definitions of dowel bending resistance (ultimate moment Mu and yield moment My), and three alternative definitions of embedment strength (f 0.05d h calculated using the 0.05 d offset method, f Fmax h calculated from Fmax, and f 0.8Fmax h calculated from 0.8 Fmax). The three lamellae layups exhibited relatively similar mean capacities (7.3–8.3 kN). The all-reclaimed connections were on average 13 % stronger than the other assemblies, but this was not statistically significant. Among the model input variants, Mu with f 0.05d h showed the closest agreement with the experimental mean values, while My with f 0.05d h led to more conservative predictions preferable for design. In both cases, excluding outliers from the embedment test results reduced overestimation in the predictions. All other input variants overestimated the shear capacity. Overall, both homogeneous and hybrid connections with reclaimed timber lamellae performed comparably to virgin timber connections and exhibited predictable mechanical behavior.
Keywords: reclaimed timber, wood densification, structural reuse, embedment strength, dowel connections, European yield model, Eurocode 5
Published in RUP: 17.12.2025; Views: 190; Downloads: 3
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3. Vibration-based serviceability and acoustic assessment of timber floorsAngelo Aloisio, Dag Pasca, Thomas Hillberger, Roberto Tomasi, Thomas Reynolds, Chiara Bedon, Sven Vallely, Rok Prislan, Kemal Edip, Mohammadreza Salehi, 2025, independent scientific component part or a chapter in a monograph Abstract: Timber floors are particularly susceptible to noise and vibration issues when compared to other construction methods, such as concrete floors. This is due to the relatively high stiffness-to-mass-density-ratio of timber floors, which enables so-called ‘lightweight’ floor constructions, in contrast to ‘heavyweight’ floor constructions consisting, for example, of concrete slabs and steel girders.
Keywords: vibrations, tall timber buildings, floors
Published in RUP: 21.10.2025; Views: 333; Downloads: 7
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5. Feasibility of portable NIR spectrometer for quality assurance in glue-laminated timber productionJakub Michal Sandak, Peter Niemz, Andreas Hänsel, Juana Mai, Anna Malgorzata Sandak, 2021, original scientific article Keywords: near infrared spectroscopy, glue-laminated timber, glulam, delamination, quality assurance
Published in RUP: 18.10.2021; Views: 4112; Downloads: 26
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8. Energy retrofitting opportunities using renewable materials-comparative analysis of the current frameworks in Bosnia-Herzegovina and SloveniaDarija Gajić, Slobodan Peulić, Tim Mavrič, Anna Malgorzata Sandak, Črtomir Tavzes, Milica Malešević, Mladen Slijepčević, 2021, original scientific article Keywords: legal framework, developing countries, existing building stock, energy efficiency, energy consumption, timber, renewable materials
Published in RUP: 04.02.2021; Views: 3686; Downloads: 74
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9. Monitoring mass timber buildings : a case study of the InnoRenew CoE buildingEva Prelovšek Niemelä, Aarne Niemelä, Andreja Kutnar, Anna Malgorzata Sandak, Jan Vcelak, Jakub Michal Sandak, Iztok Šušteršič, 2020, published scientific conference contribution abstract Keywords: sustainable architecture, mass timber buildings, CLT, structural monitoring, hygrothermal monitoring, timber façade, microclimate
Published in RUP: 07.08.2020; Views: 4259; Downloads: 94
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