Experimental and analytical assessment of the lateral loading response of a full-scale hybrid timber structure incorporating a structural glass diaphragm

Abstract

This study examines the contribution of a structural glass window integrated into a lightweight timber-frame wall diaphragm at the structural level. A full-scale timber mock-up, comprising different bracing elements such as wall diaphragms (with and without a bonded structural window), and a moment-resisting frame, combined with a roof diaphragm, was subjected to multiple serviceability limit state horizontal loadings. The experimental program was repeated for configurations with and without the structural glass window to enable direct comparison. In addition, the experimental results were complemented by analytical modelling based on second-generation Eurocode 5 formulations, extended to account for adhesive deformation at the timber-glass interface. The results demonstrate that integrating a structural glass window enhances diaphragm stiffness by approximately 13%, demonstrating that the Eurocode 5 provisions, which ignore the panel containing the window's contribution, are overly conservative. The measured load distribution to each bracing element also indicated that a larger part of the applied horizontal load was transferred to the diaphragm with the structural window. At the structural level, reduced roof and frame deformations were observed, confirming that local wall stiffening results in reduced global displacements. Tensile/compressive force distributions measured at the foundation level indicated that the presence of structural glass did not significantly alter the distribution and corresponded with the provided elastic models. Finally, the analytical predictions substantially underestimated absolute stiffness values but captured the relative increase in stiffness due to structural glass. The findings highlight the importance of system-level effects and support the structural use of glass in hybrid timber systems.