Requirements for Balustrade Assembly using the example to the left
200 lb Concentrated Load (recalculate as necessary for 300 lb load)
f = M/S
f = Modulus of Rupture (mean)/Safety Factor
f = 24,000/4 = 6000 psi (maximum allowable stress)
M = h x P = 38 in x 200 lb = 7,600 inlb
Section Modulus for 1/2" glass (0.469" is the minimum ASTM standard for nominal 1/2" glass; assuming a 48" wide panel)::
S = (w x t^{2})/6 =(48" x .469^{2})/6 = 1.759 in^{3}
f = M/S
f = 7,600 inlb/1.759 in^{3} = 4,320 psi
4,320 psi < maximum allowable stress of 6,000 psi therefore 1/2" tempered glass is acceptable
