Lifetime strength model for laminated glass plates based on modified stress-effective thickness

Laminated glass is widely used in construction due to its unique transparency and structural functionality, yet accurately predicting its lifetime capacity remains a challenge. This difficulty arises from the significant load history dependency, which is induced by the viscoelastic property of polymeric interlayer and the stress sensitivity of micro-cracks growth on glass surface. This study presents an analytical framework to assess the lifetime capacity of laminated glass plates by integrating a modified stress-effective thickness model with a lifetime strength model. Firstly, a new model to determine a more accurate stress-effective thickness of multi-layer laminated glass was proposed by acquiring the closed-form solution of interlaminar shear stress of interlayer. The proposed model was experimentally validated and then compared with enhanced effective thickness (EET) method and finite element (FE) methods. Results show that the proposed method achieved improved accuracy in determining the stress state within laminated glass. A glass lifetime strength model was then developed based on the micro-crack growth principle and failure criterion, with calculation procedures provided for both constant and general stress states. By combining these two components, a design method for estimating the lifetime capacity of laminated glass was formulated. A case study was conducted to illustrate the design procedures and highlight the evolution of glass stress and strength throughout service life. The proposed analytical framework establishes a direct analytical link between structural stress and flaw-driven fracture, providing a foundation for future probabilistic or reliability based analyses of laminated glass structures. • Modified stress-effective thickness (MSET) model was developed. • MSET model has higher applicability in certain conditions. • The polymeric viscoelasticity and long-term micro-crack growth were introduced. • MSET and long-term behaviour was used in the lifetime strength model of laminated glass.