I am looking at some old drawings and I noticed that for some for the steel shapes there is a number next to it in parenthesis. For example, in a roof plan it would say por one of the beams C8X11.5 (-2"). What does the -2" mean?
We need to make some openings on a metal roof deck (1970, 18ga, 1.5"B). What is the effect of these new openings on the deck in terms of strength decrease? I read in an old catalog that openings cannot sum up to more than 0.5% of the entire deck area, but I haven't read that anywhere else.
I'm working on some roof openings for an old factory. A X-brace located in the roof (horizontal bracing) interferes with one of the openings. Is is possible to cut part of this member and attach the remaining length of it to one of the shapes that will be part of the framing for the opening...
