294 Failure Criterion

where P60 is the constant pressure causing failure of the panel in 60 s and Pf is the constant pressure causing failure at a duration of Tf s.

The use of a design factor of 2.5 has been introduced to control the POF to 0.008. The POF can be expressed in terms of Weibull distribution as follows:

where B is a function that reflects the risk of failure and is given as where e is a natural number, A0 and S0 are the area and characteristic strength of the reference glass panel, respectively and A and Smpr are the area and characteristic strength of the glass panel, respectively. Sm,p,r is a function of the Weibull parameter, m, pressure, p, and aspect ratio, r. Failure data for in-service glass were collected (see Ref. [12]) and fitted to Equation 29.5. The fitted Weibull parameters m = 7 and S0 = 32.1 MPa are adopted in Canadian Code, and the reference area, A0, is equal to 1 m2.

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