Architectural glazings: Design standards and failure models

Architects and glass designers often refer to published standards when selecting glass thicknesses and areas for glazings in buildings. Glass design standards generally are based upon the results of experiments involving the breakage of standard sized glass sheets under carefully controlled conditions. More recently, some design standards have incorporated mathematical failure models which contain empirical parameters whose values have been estimated from these same experimental studies. In this paper, the technical basis for the recommendations within current architectural glass design standards is discussed. Existing glass failure prediction models are reviewed and it is shown that significant discrepancies exist between their recommendations and those of the design standards. A modified crack growth model is proposed which predicts failure probabilities for both short and long term stresses which are consistent with established design practice.