Design of supported floor for AASHTO loading

[denoid]

In the near future, I will be designing a county garage building on horrible soil conditions. The building will need to be on piles, grade beams, etc. The architect also wants to use precast floor members.

I believe the trucks will fall under the H-20 load conditions, but I'll have to check that.

I haven't worked much with AASHTO loadings in the past, but I basically know the procedure. I don't think a high impact factor is warranted, since the trucks will be pulling in slowly and parking, but I'm unsure of a factor to use. Maybe, 20% to 25%? Also, is there some approximate equivalent uniform load to match AASHTO H-20 loading to check my design? Much of the space will not be heavily loaded, except in the parking stalls, but the middle is a traffic lane, and there are no live load reductions for such heavy loads. I hate to penalize the number of piles required by considering a large, unreducible live load over the entire area, when much of the building is typically empty, (ie. the drive lane).

Any thoughts or ideas?

 

[samdamon]

Confirm with your client that you do not have to support a fire truck inside the building. I very rarely need to use AASHTO so will let others more familiar with it comment on your other concerns.