Point load distribution in retaining wall
Point load distribution in retaining wall
(OP)
Hi everybody,
I am in the process of designing a concrete cantilever retaining wall which will have a vehicle barrier attached to the top of it. I was wondering about the method of distributing that point load (AASHTO 10 kip) over the height of the wall to find the moment-per-foot at the base of the stem. General knowledge says that the stress will distribute at a 45 degree angle in each direction, thus making the distribution width = 2*h. However, I seem to remember seeing something in a code about the distribution width being =h instead of =2h. It may have been in ACI of AASHTO, but I can't see to find it. Does anybody have any insight on this?
I am in the process of designing a concrete cantilever retaining wall which will have a vehicle barrier attached to the top of it. I was wondering about the method of distributing that point load (AASHTO 10 kip) over the height of the wall to find the moment-per-foot at the base of the stem. General knowledge says that the stress will distribute at a 45 degree angle in each direction, thus making the distribution width = 2*h. However, I seem to remember seeing something in a code about the distribution width being =h instead of =2h. It may have been in ACI of AASHTO, but I can't see to find it. Does anybody have any insight on this?






RE: Point load distribution in retaining wall
Either way, if your wall seems excessive in size then I'd consider using a moment distribution slab and have the rail tied into it. Sometimes I think this is the easiest alternative.
RE: Point load distribution in retaining wall
As for the 10 kip load, its 6 kips service which is 9.6 kips ultimate. This load occurs at 18" above the road surface and acts on a 12"x12" square (18" barrier is unacceptable, 24" min).
RE: Point load distribution in retaining wall
I have designed many retaining walls with considering impact loads, and I have used a 45 degree distribution with acceptable results. As Teguci has mentioned consider what you're designing for. For localized wall bending and shear I would use more conservative distribution widths. However, if you are considering overall wall overturning you could use a larger distribution, because the whole wall will act to resist the overturning, provided you don't have a localized failure first.