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Description:
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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 . |