Study on the effect of geometric nonlinearity on uneven load distribution in multi-glazed insulating glass units

Accurate and efficient evaluation of the load-bearing performance of multi-glazed insulating glass units (IGUs) under uniform loads is essential for wind-resistant design and safety assessment of glass curtain wall systems (GCWS). However, existing empirical data and numerical models are insufficient for reliably capturing the mechanical behavior of these novel thin-shell components, particularly for large-deflection analysis. This paper presented and validated two different finite element (FE) modeling methods, considering geometric nonlinearity, material nonlinearity, and uneven load sharing. Simply Supported (SS) and Center Constrained (CC) boundary conditions were used to build three FE models. Their accuracy, computational efficiency, and applicability were discussed and compared with the BAM method. Based on the superior 2-CC method, the effect of cavity thickness on load sharing ratios (LSRs) of quadruple glazed IGUs (QIGUs) was analyzed. It is found that the LSRs vary with load magnitude, and for the currently used Type A product, designing based solely on the stiffness distribution method adopted by the ASTM E1300 may lead to an underestimation of the LSR for Pane 1 by over 30 %, while overestimating the LSR for Pane 4 by nearly 50 %. Furthermore, a parametric analysis was conducted to determine the LSRs for ten types of market-available QIGUs, as preliminary improvements to the stiffness distribution method. Finally, an optimized calculation formula was presented, providing a basis for conventional QIGU design and a reference for future lightweight optimization analysis of multi-glazing components.