steel calculation shall be prepared on the basis of structural drawing only. you have to finalize the vendor first,collect the drawing from him, submit the same to the structural consultant who will design the entire drawing. without this you cannot derive any quantify.
there are varieties of s,t.p namely 1.sm.b.r, 2 m.b.r, 3. m.m.b.r etc. refer the m.e.p section . already i have posted a presentation on stp.