basment wall design

huangyhg

basment wall design
i am designing my own house and i am planning on using spancrete hollow core planks to span my garage.  problem is i don't know how much reinforcing to put in the walls. the spancrete guys will not do the design work for the walls they just engineer the planks. i am looking for some advice.  i am going to have the basement wall where the spancrete rest, 10' tall 10" thick with a 4" interior ledge to support the spancrete at 8'tall.  the spancrete wieghs 57psf plus 50 psf for 4" thick concrete on top of.  the walls will be backfilled to 8'.  can anyone give me an idea of how much reinforcing i will need in the wall/ledge.  the soil is clay.  i am planning on getting a engineer to engineer the walls, but i want to know if this will be cost prohibitive due to the amount of rebar. the concrete contractor has told me that if allot of rebar is used the cost goes up significantly and i don't want to start this project then not be able to do it and have a bunch of money already in it for the engineering of it. thanks in advance for any help that you may offer.  sincerely, scott
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your wall is not particularly tall so it shouldn't need a huge amount of reinforcement. it is of a reasonable thickness too. if you can use the spancrete planks to prop the wall then you should not be using much more than minimum reinforcement anyway. if you engage an engineer he or she will advise you on the details of how to make sure the spancrete is connected into the wall correctly. the spancrete guys will need to know about this too for their design.
carl bauer
torak:
in my area of the country, midwest u.s.a., to furnish and install reinforcing steel costs around $0.65 - $0.75 per pound ($1,300 - $1,500 per ton) for #4 and #5 in a wall.  i could be a little less for residential construction.
one other caution, before backfilling the wall be sure that either the spancrete is set in place or the wall is braced.  don't let the backfill be placed against an unbraced wall. it will push it over or at the least badly crack it.  
good luck.
you did not state if the wall is masonry or poured concrete!
you can look at the national concrete masonry asst. tek 15-1a or tek 15-2a for a guideline. i don't kno if that phamplet is available on line or not.
the reinforcing will be similar for either masonry or concrete.