Basement/Retaining Wall Surcharge 1

[BadgerPE]

Hey all!

Is it common practice to design with a construction surcharge behind cantiliver retaining walls and basement walls (restrained by floor at top)? I have been running the AASHTO 250 psf load but it increases the dimensions of the wall considerably on taller walls. If you use a construction surcharge, what loading do you use and do you have any code sources to back it up? Any info would be greatly appreciated.

 

[minorchord2000]

For these types of walls which I am assuming is for a residence, I would only use 1 foot of surcharge. I think it is sufficient for this type of construction. 250 psf is more like 2 feet of surcharge. If the wall is restrained at the top, you would probably about 60 psf/ft active lateral pressure and 1 foot of surcharge is equiavalent to 1*60 = 60 psf lateral load along the wall height.

 

[dhengr]

Today’s codes dictate way too much already, and still they don’t tell you everything about everything, and cover every situation, no matter how hard they think they try. Maybe this surcharge issue will be included in the next edition of the codes; a surcharge for kids tricycles, one for small vs. large gas grills near the bldg., another for parked cars along side the bsmt. wall, etc. etc. I think you are mixing apples and oranges here; retaining walls (truly cantilevered) governed by AASHTO are not the same as residential bsmt. found. walls. A residential found. wall is not usually a canti. retaining wall, rather it is laterally supported at the top by a floor diaphragm. It is not reasonable to assume a fully loaded dump truck will transit within 2' of a bsmt. wall. That’s the trucker’s fault. You add a surcharge loading when one can be reasonably anticipated. And, you spec. and say in your structural notes on the drawings; that walls should be fully braced during backfilling, and that they shouldn’t use anything larger than a D783 CAT for backfilling.