I'll try to describe a little better as to what my question was.
I have a concrete pit which will eventually contain machinery and the floor decking will be subject to pedestrian traffic only. However,before the machinery is installed, the pit will have to be plated over temporarily. At this time, the decking will be subject to scissor lift traffic for overhead work.
The pit is 26'-6" long x 16'-6" wide. I had planned on placing a beam 26'-6" long on the centre line of the pit,welded at each end to the curb channel of the pit and having (2) 4" dia pipe supports each one being 8'-4" from each end. Perpendicular to this beam I would have beams 16'-6" long at 2'9" centres again each end welded to the curb channel and resting on top of the centre beam. The pit would then be plated over with 3/8" plate, each plate being cut to 2'-9" x 8'-3" so that they have bearing on all four sides on the steel.
The scissor lifts would be 3400 lbs including the men on board.
Designing for a load of 150 psf could I take a strip load on the centre beam of 8.25 x 26.5 x 150 = 32793.75 lbs then divide by 26.5 to give me a distributed load of 1237.5 lbs/ft or is this beam subject to several point loads ?.
For the perpendicular beams, I could do the same using 2.75 x 8.25 x 150 = 3403 lbs , divide by 8.25 for a load of 412.5 lbs/ft.
This seems overly simple,but I have used a piece of software called BeamBoy and the results I get tell me that I can us S6 x 12.5 sections for the support steel throughout.
On the perpendicular beams for example the results look favorable :Def.of 0.027" Max M of about 1800 lb-ft and bending stress of about 2900 psi.
Using the same method on the centre beam the results are
Def. of 0.09" Max M of 5900 lbs-ft and stress of about 10000 psi.
This seems OK or am I missing something? The choice of s6 x 12.5 is because we have miles of it on hand and it is temporary.
Thanks for any help in advance.