Load resistance charts for heat-treated window glass

Major U.S. glass manufacturers such as LOF/Pilkington and PPG Industries, Inc. once supplied design recommendations in the form of glass thickness selection charts. These charts enabled users to select an appropriate glass thickness based on required design pressures and glass area. ASTM standardized these charts into a set of nominal thickness selection charts for Annealed (AN) window glass. At the same time ASTM provided strength factors to accommodate for the design of Heat Strengthened (HS) and Fully Tempered (FT) window glass.

ASTM El 300 (1997) assigns HS glass a strength twice that of AN window glass having the same geometry. Similarly, ASTM assigns FT glass a strength four times that of AN window glass with the same geometry. Even though it is not clear how these factors are selected to represent the two glass types, they are widely accepted by glass designers and manufacturers over the world.

While this thesis takes a more theoretical approach, it does not alter the traditional factors radically for the minimum values of residual compressive surface stresses (RCSS). However, the development of the new load resistance charts for HS and FT window glass is based on specific criteria through mainly theoretical veins, due to the paucity of experimental data for HS and FT window glass lites.