Simulating the thermal response of glass under various shading conditions in a fire

Abstract

In a fire, the thermal stress upon window glass caused by a temperature difference between exposed and shaded areas is the key factor contributing to glass fracture. The purpose of this study is to investigate the effects of different shaded conditions on the glass when it is exposed to fire. Eleven different shading cases were simulated using finite element method (FEM) software, called EASY, which was developed by the authors and verified accurately by theory. The glass surface temperatures, stress field, the time and location of crack initiation and crack propagation were presented. It was found that the center shaded case is a safer way to protect the glass from cracking, and the four corners shaded case has greater probability of cracking. The stress and fracture models for shading glass can be applied in predicting the probability of crack initiation, the distribution variation of temperatures and the stress time history under certain thermal loads. Furthermore, practical advice to optimize the window installation design or ways of shading to protect the glass from falling out in a fire can be obtained from the results. © 2013 International Association for Fire Safety Science.