steel beam supporting garage

[onlyinamerica]

I have a garage that is 24' deep by 36' wide. To bring the garage up to grade I had to have 7' high block walls built due to the sloping plot. The block walls were then backfilled inside and out with no compaction. I have heard that placing steel I beams to grade and then pouring over them would offset much of the settling that would occur and (help to) minimize any large cracking in the pad. Since most of the load occurs where the cars will be parked would placing a beam in each bay and using 3500 psi do the trick? I will also be installing radiant heat into the garage attached to steel fencing that will help a bit. Thoughts? Please no referrals to S.E.'s.

[Pokey]

What did you back fill the garage with? I would avoid the steel beam below you slab by compacting your fill if at all possible.

[Zatol]

If much fill is needed, I'd backfill with stone. No compaction needed and less pressure is put on the garage walls.

[onlyinamerica]

The entire garage has been backfilled with dirt. Stone on the top 6/8 inches. The reason I didn't compact it was for a couple reasons. I've been told by numerous fellow contractors that the ground is going to settle no matter how well you try to compact it. part of that I have to agree with. To compact the soil for that size would have taken days and that's a lot of time spending if it's going to settle anyway. With a loader you aren't going to get nice little 6 or 12" lifts so quality of compaction would have been compromised. They've seen cracks no matter how well you compact it but have had great results with the Ibeam approach.

I was going to consider filling the block where the beam will rest with concrete to help support the beam as it will take a fair amount of load when the dirt settles. Would you suggest a stick or 2 of rebar?

Thanks