Finite element modelling of the structural in-plane shear behaviour of hybrid timber–glass diaphragms for BIPV applications

Abstract

Innovative structural systems, such as timber-glass diaphragms with integrated photovoltaics, can only be adopted in practice if reliable and validated design methodologies are established. To this end, the present study develops and validates two structural finite element modelling strategies that aim to balance between computational efficiency and predictive accuracy. The hybrid timber-glass system under consideration, where the glass panel contributes to the in-plane stiffness of a timber frame, has been experimentally investigated in a previous study [Engelen, 2025] and serves as the basis for model calibration and validation. The first model, developed in COMSOL Multiphysics, is calibrated using small-scale connection tests. The adhesive bonding between the timber and glass is modelled with a hyperelastic material model, including phase-field damage to model material failure. This detailed modelling approach accurately predicts the overall stiffness and strength of the diaphragms and enables detailed analysis of strain distributions through the glass thickness and within the solar cells. Despite its high precision, the model's computational cost is substantial. Therefore, a second, simplified model is created in an engineering software package, Buildsoft Diamonds. This enables faster assessments in engineering practice, offering acceptable accuracy with less computational effort. Finally, both models are employed in a parametric study to identify which design factors, such as aspect ratio, glass thickness, and adhesive size, affect the stiffness of the diaphragms.