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Behaviour of glass plates under pressure loading

Glazing damage during strong windstorms has been considered to result mainly from windborne debris. However, recent windstorm damage reports have revealed the necessity of studying fluctuating wind loads, which appear to be another factor contributing to this damage.

experiment setup From an experimental point of view, studies on this topic have been limited to the application of rather simple loading patterns. Moreover, there is an uncertainty surrounding both load resistance and design load used in the current North American window glass design codes.

It is of concern that these regulations may not offer sufficient accuracy on account of the limited understanding of time-dependent glass strength derived from the technology available at the time of codification. Unprecedented full-scale glass breakage tests under realistic wind pressure loading were conducted to investigate these issues (Figs. 1 and 2).

The obtained results revealed significant new information about the behavior of glass plates under fluctuating loads. Along with these tests, a numerical simulation using the Monte-Carlo technique was also performed with a subtle modification of the initial glass strength. This adjustment resulted in better correspondence with test results.

failure pressure level of glass plate under fluctuating load

Using the test and numerical simulation results, the current window glass design method was examined. The calculation methods of LR, and the reference time conversion used in the codes, were found to require further investigation (Fig. 3).

comparison of load resistance between codes and the numerical simulation

By creating a particular wind pressure time history, the practice of using peak pressures from ASCE7-05 as the design load was investigated. The results showed that there are cases when the current practice may underestimate the design load because of the duration of windstorms.


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Updated August 12, 2010 by contactWE
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