The design for glass used in floors, landings, stair treads and similar locations shall be determined as indicated in Section 2409.4 based on the load that produces the greater stresses from the following:
1. The uniformly distributed unit load (Fu) from Section 1607;
2. The concentrated load (Fc) from Table 1607.1; or
The dead load (D) for glass in psf (kN/m2) shall be taken as the total thickness of the glass plies in inches by 13 (For SI: glass plies in mm by 0.0245). Load reductions allowed by Section 1607.9 are not permitted.
Laminated glass having a minimum of two plies shall be used. The glass shall be capable of supporting the total design load, as indicated in Section 2409.4, with any one ply broken.
Glass in floors and sidewalks shall be designed to resist the most critical of the following combinations of loads:
Fg = 2Fu + D
(Equation 24-11)
Fg = (8Fc /A) + D
(Equation 24-12)
Fg = Fa + D
(Equation 24-13)
Where:
| A | = | Area of rectangular glass, ft2 (m2). |
| D | = | Glass dead load (psf) = 13 tg (for SI: 0.0245 tg, kN/m2). |
| tg | = | Total glass thickness, inches (mm). |
| Fa | = | Actual intended use load, psf (kN/m2). |
| Fc | = | Concentrated load, pounds (kN). |
| Fg | = | Total load, psf (kN/m2) on glass. |
| Fu | = | Uniformly distributed load, psf (kN/m2). |
The design of the glazing shall be based on
Fg ≤ Fga
(Equation 24-14)
where Fg is the maximum load on the glass determined from the load combinations above, and Fga is the maximum allowable load on the glass, computed by the following formula:
Fga = 0.67 c2 Fge
(Equation 24-15)
Where:
| Fge | = | Maximum allowable equivalent load, psf (kN/m2), determined from Figures 2404(1) through 2404(12) for the applicable glass dimensions and thickness; and |
| c2 | = | Factor determined from Table 2404.2 based on glass type. |
The factor, c2, for laminated glass found in Table 2404.2 shall apply to two-ply laminates only. The value of Fa shall be doubled for dynamic applications.