PSI - Issue 78

Florence More et al. / Procedia Structural Integrity 78 (2026) 944–951

950

accelerated wetting/drying (W/D) cycle that replicated the natural MC fluctuations observed in timber bridges, ranging between 10% and 30%. A key innovation was embedding strain gauges within the glue lines of glulam specimens to monitor internal strain responses, distinguishing between inner and outer lamellae. The bonding pressure during glulam manufacturing did not impair the gauge's function and the embedded sensors effectively recorded moisture induced strain differences. These findings demonstrate that internal moisture gradients lead to differential swelling and shrinkage, causing internal stresses that can initiate cracks and reduce structural durability. The current landscape of SHM research in timber structures reveals a growing convergence of digital tools, sensor technologies and structural engineering principles. Although considerable progress has been made, challenges persist, particularly in calibrating monitoring systems for anisotropic wood, handling large volumes of real-time data and adapting SHM frameworks for application in historical contexts. Future efforts should prioritise the refinement of NDT methods, the development of cost-effective and scalable monitoring systems and the integration of SHM data into life-cycle-based design and conservation protocols. 4. Conclusions The advancement and application of SHM in timber structures have become increasingly critical due to timber's inherent anisotropy, hygroscopic behavior and biological vulnerability. Through the integration of multi-modal sensing technologies, such as strain gauges, accelerometers, acoustic emission sensors, fibre Bragg grating sensors and embedded electrical resistance-based moisture sensors, SHM enables continuous, real-time assessment of both structural and environmental performance parameters. This review has outlined the operational principles, deployment strategies and performance characteristics of SHM techniques specifically adapted to timber structures. The synthesis of case studies and recent developments demonstrates that environmental variables, particularly temperature and moisture content, induce significant modulations in dynamic properties such as natural frequencies and damping ratios. These modulations underscore the necessity of integrating environmental compensation algorithms and hybrid sensing frameworks to reliably detect and quantify damage signatures. The incorporation of SHM into engineered wood products (e.g., CLT, GluLam, LVL) during fabrication, combined with the use of wireless sensor networks and digital twin models, offers a scalable pathway for lifecycle monitoring, structural diagnostics and predictive maintenance. However, challenges persist in calibrating sensors for timber’s orthotropic and non -linear behavior, ensuring long-term sensor durability and standardizing SHM protocols for widespread industry adoption. Future research should prioritize the development of moisture-compensated diagnostic algorithms, enhanced sensor durability under variable field conditions and harmonized SHM frameworks tailored to timber’s material -specific degradation mechanisms. The convergence of SHM with advanced computational models and machine learning techniques holds the potential to transform timber infrastructure into intelligent, self-diagnosing systems, thereby enhancing structural resilience, extending service life and supporting sustainability objectives in modern construction. 5. Acknowledgments This study was partially funded by the research project DPC-ReLUIS 2024-2026, WP6 – Structural Health Monitoring and Satellite data, promoted by the Italian Civil Protection Department. References Aloisio, A., Pasca, D. P., Kurent, B., & Tomasi, R. (2025). Long-term continuous dynamic monitoring of an eight-story CLT building. Mechanical Systems and Signal Processing, 224, 112094. https://doi.org/10.1016/j.ymssp.2024.112094. Amaddeo C., Dorn M., Martinelli L., (2025). Initial monitoring of a six-story lightweight timber frame building under different environmental conditions. Journal of Civil Structural Health Monitoring, 15(2), 371-393. Angelo Aloisio, Dag Pasquale Pasca, (2023). Vibration issues in timber structures: A state-of-the-art review. Journal of Building Engineering, 76, 107098. https://doi.org/10.1016/j.jobe.2023.107098. Arda Buyuktaskin, H. A., Yatagan, M. S., Erol Soyoz, G., Tanacan, L., & Dilmaghani, M. (2019). Experimental investigation of the durability of load bearing timber-glass composites under the effects of accelerated aging. Journal of Green Building, 14(2), 45 – 59.