Cracking behavior of glazings with different thicknesses by radiant exposure

Abstract

Fourteen experiments on cracking behavior of glazings with thicknesses of 3, 6, 8, and 10 mm by radiant exposure were carried out with a new experimental apparatus. The radiant power was controlled proportional to time square to simulate a time‐squared growth fire. An infrared thermal imaging camera was employed to monitor the temperature field of the unexposed glazing surface. Other important parameters including incident heat flux, local gas temperature, exposed surface temperature, and time of the first cracking were obtained. The relationship between the cracking behavior and glazing thickness was analyzed based on the experimental results. The results show that the protected edge temperature of glazing has a considerable rise when the first cracking occurred, which should be included in further modeling. It was also shown that thicker glazings have smaller surface temperature during the heating process and induce longer time to first crack. However, the critical temperature difference approximately remains constant for all glazings studied. Copyright © 2011 John Wiley & Sons, Ltd.

A Probabilistic Model for the Fallout Area of Single Glazing under Radiant Heat Exposure

“…Results from the experiments showed that no fallout occurred below an average heat flux of 20 kW/m 2 . This is in line with the findings by Li et al [19] whose research has shown that a radiant heat flux of only 4-5 kW/m 2 caused glass cracking but did not cause glass fallout. The glass cracking heat flux limit of 4-5 kW/m 2 has also been proposed by Mowrer [20] and it has been widely accepted as a glass fallout criterion.…”

Evaluation of Monte Carlo method for modeling glazing behavior during radiant exposure

“…Comparision between the tested and MC-Glaz predicted temperatures of the exposed glazing surface for Test 12, 10 mm galzing, relative errors are also provided. Reproduced with kind permission from Wiley [23]. Because of data limits, only pan fire sizes of 0.6 m  0.6 m and 0.9 m  0.9 m were considered [7].…”

“…The experimental conditions of Test 1 for 3 mm glazing and Test 7 for 8 mm glazing from [23] are used to examine these influencing factors. Figure 14 shows that the time of first cracking increases with an increase of s/H ratio, while it decreases with an increase of Young's modulus.…”

“…The experimental condition of test 11 [23] is used to study these two influencing factors. The temperature histories for 3, 6, 10, and 30 mm glazing before the time of first cracking are shown in Figure 12.…”

“…Comparision between the average-tested and average-predicted time of the first cracking for[23].were used: max ¼ 70 MPa, E ¼ 70 GPa, ¼ 8.8 Â 10 À6 /K, c p ¼ 820 J/(kg K),k ¼ 0.95 W/(m K), and ¼ 2500 kg/m 3 . The geometry of the glazing was: L ¼ 6 mm, H ¼ 422 mm, and s ¼ 15 mm.…”