Development of design and analysis methods for window structures against blast and impact loads

[Truncated] Terrorist bombing and accidental explosion threats have brought to light the need for better analysis and design of occupied facilities for personal protection. Understanding glass window performance subjected to blast loadings have attracted a lot of attentions over the past years, because glass window has relatively low strength among building structural components therefore it is considered particularly vulnerable under impact and blast loadings. Post-event investigations of explosion incidents have also found the failure of glass windows and the associated flying glass fragments as one of the major threats to residents.
This thesis presents a study into the analysis and design of blast and impact resistant window systems. Architectural annealed glass material properties are tested and used to form dynamic material model for glass. Dynamic material properties of two types of popularly used interlayers for laminated glass, namely Polyvinyl Butyral (PVB) and SentryGlas®Plus (SGP by DuPont®), are also tested and the corresponding dynamic material models developed. Numerical and experimental studies are performed to investigate the behaviour of monolithic glass and laminated glass windows.
Glass is a brittle material. Most previous studies used a linear elastic material model with glass compressive and tensile strengths from static tests. However, as is known material strength normally depends on loading rate. Simply adopting glass static material strength will greatly underestimate glass capacity especially under blast and impact loading where material deformation rates are high. In this study, Split Hopkinson Pressure Bar (SHPB) tests are carried out on architectural annealed glass. Both the dynamic compressive strength and tensile strength are derived from tests at various strain rates. The dynamic increase factors (DIFs) are determined. The glass fracture process is also investigated together with glass fragments to explain the testing results.
Currently integrated dynamic material model for architectural glass is very limited. With the dynamic material testing results on annealed glass and previous testing data reported by other researchers, the popularly used Johnson Holmquist ceramic (JH2) model is modified to simulate architectural annealed glass. The material constants for strength model, strain rate effect, equation of state and damage model are determined with laboratory testing data. The modified model for glass material is verified with a SHPB compressive test on glass specimen, a field blasting test, and a debris impact test. The simulations find the modified model give accurate representations of glass material performance under blast and impact loads.