Basement Retaining Wall - Buttress Addition

[JohnnyB_]

Hello -

I am designing a basement retaining wall that is 60' long by 13' tall. The home owner is adamant on providing two buttresses in the basement of the retaining wall. My question is, with addition of the buttresses, will a two-way slab action be created?

Thanks in advance.

 

[HouseBoy]

Some observations (from experience):

It will be difficult to make the wood floor connection to the top of the wall sufficient to resist the horizontal load from the soil that will result if the wall is only spanning vertically. 5/8" bolts at 48" o.c are not going to cut it (hint - the sill plate is a weak link)

The buttresses MIGHT help reduce wall deflection (maybe only slightly) however, they will not resist much load (such as if the wall wants to span horizontally) UNLESS there is a significant footing located at the buttresses. Also, I would expect the length of the buttress (measured perpendicular to the wall) to be great IF it is going to be effective. It's true that the heal of the footing will help some but I would def be concerned about soil bearing pressure in the toe. With the buttresses doing a lot of work, there would be A LOT of load going out into the heal in the vicinity of the buttress. I would expect a lot of steel reinforcing would be needed near the buttresses IF that is going to work. Larger footing at the toe side woful be a simpler analysis (I would think).

IF the wall is going to span horizontally to the buttresses, THEN I'd have the horizontal #5 bars in both fees full height.

I don't think this wall works unless the buttresses are truly capable of resisting the load that they WILL attract.

 

[PEinc]

I have the same questions as JLNJ and XR250. Basement walls that are braced or restrained at their top usually, in my experience, do not have a wide heel projection behind their outside wall face. Your footing looks more like a cantilevered wall footing than a top-restrained basement wall. Do you have sufficient dead load to prevent sliding?

http://www.PeirceEngineering.com

 

[JohnnyB_]

PEInc - The large heel is to decrease the bearing on the soil. I am using 1500 psf due to a lack of soil information. The 60'x40' basement floor slab is restraining any sliding that may want to occur.