Flaw Characteristics of Architectural Glass and Long-Term Strength Prediction Model

Architectural glass has been widely used in modern buildings due to its aesthetics and functionality. The growing use of glass in load-bearing structures raises concerns about its long-term strength due to the existence of the flaws and subcritical crack propagation. Better understanding of flaw characteristics is crucial for evaluating the mechanical properties. However, existing knowledge on flaw characteristics is limited, and the load duration factor kmod specified by standards doesn't consider different stress histories. This paper aims to fill these gaps by observing and analysing the flaw and statistical characteristics in glass, especially the edge defects, proposing a Monte-Carlo based model to simulate the long-term mechanical behaviour of glass specimen with distributed edge defects and modifying the kmod. 3D laser confocal microscope was utilized to observe the defects. The Monte-Carlo based model is able to generate edge defects and conduct numerical experiments to expand the data pool. Based on stress corrosion theory, the crack resistances under two load conditions (constant stress and constant stress rate) were derived respectively. By analysing and quantifying the influences of temperature, humidity and stress rate on crack growth parameters, the crack resistances under two load conditions are compared, and a modified kmod is then proposed. The Monte-Carlo based model is verified by lifetime test from literature. The modified kmod is validated with substantial dataset across various load durations and is compared with international standards, demonstrating the accuracy in predicting glass long-term strength.