I have a client that has salvaged some steel joists from a commercial
structure and wants to use them in a garage structure. These joists are 18
inches deep. The top chord is comprised of 2 angles, 3/8 inch thick with 2
inch equal length legs. The webs are 5/8 inch steel rods and the bottom
chord is constructed using 2 7/8 inch rods. The salvaged pieces are
approximately 31 feet long (some are slightly longer as it appears that they
were cut by a torch). The Steel Joist Institute provided a reasonable guess
that they are an 18H8 series. They estimated the joists to be from 1979 when
the H series was in effect.
Does anyone know how to evaluate the strength and stiffness of these joists?
What is your opinion of using these in this structure (second story floor at