Thermal cracking prediction of frameless glazing exposed to radiant fluxes increasing with height

Abstract

SummaryThe prediction of losing integrity of glazing elements exposed to compartment fires is important in building fire safety. Existing criterion is only appropriate for framed glazing but not frameless glazing due to omission of the flexing stress in the former. A robust and directly applicable expression to determine the location and time of thermal cracking of frameless glazing is lacking in the literature. In this work, thermal stress calculations including the effect of flexing stress were performed based on typical temperature distributions of glazing exposed to compartment fires, and then simple expressions of the maximum stress were derived. Besides, experiments of frameless glazing exposed to heat radiation were carried out to verify the applicability and accuracy of the obtained expressions, as well as to investigate the cracking behavior of frameless glazing. Results show that the proposed expression of maximum stress agrees well with the experimental cracking behavior. Cracks start from the bottom edge and the upper edge of the glazing when exposed to typical distribution of radiant fluxes from compartment fires. In addition, flexing stress has significant contribution to the total stress field.