On page 43 of the Commentary to WFCM, in footnote 2 they make a jump from p=51.4 psf to p=85.65 psf. The equation that is used is not mentioned and only values are used: p=[51.4 psf]/[(cos26.6))(cos(26.6))/(16 in./12)]. So the formula is p(new value) = p(old value)/cos^2. They went from the assumption of a horizontal plane projection to a sloped projection (the original roof) and a force normal to that slope. My trig is a little rusty and I am lost as to why this equation.
What formula are they using and where did it come from?
Any help would be appreciated, thanks.
What formula are they using and where did it come from?
Any help would be appreciated, thanks.
