AASHTO requirement for wheel setback from wall
AASHTO requirement for wheel setback from wall
(OP)
Sorry to ask the question but I am not a structual. However the county is required to review plans submitted by engineers. It is required that for this design it should be a registered structual however in Washington laws allow a civil to perform if they feel competent. My question is that there is a creek crossing, 14 foot culvert, that a retaining wall is proposed for a new road crossing, and the wall is proposed to set 1 foot above existing steel culvert (thought had to be minimum 2 feet). The engineer states he can use a uniform load for meeting AASHTO for H20-40 by allowing the wheel up against the wall (road is narrow) and assumed uniform load of 2 feet equivalent height or 250 psi. I look at the AASHTO and it looks like for 2 feet eq. height the wheel is assume 5 foot offset? Can you help? I am worried the wall is going to slide toward creek.






RE: AASHTO requirement for wheel setback from wall
If the wall has impact, then it should be at 1.75' above the grade to the impact location. Either a parapet of guide rail will be needed if impact is required.
Just check what pressure he used for his surcharge. If he used 250psi, that seems high. It should be 250psf I think.
RE: AASHTO requirement for wheel setback from wall
RE: AASHTO requirement for wheel setback from wall
RE: AASHTO requirement for wheel setback from wall
Why is he using a HS-20 load with LRFD surcharge design? It should be HL93 truck with LRFD, or 2' surcharge with the HS-20 vehicle.
RE: AASHTO requirement for wheel setback from wall
RE: AASHTO requirement for wheel setback from wall
250 psf is usually used for highway traffic, given that it is a reinforced concrete wall it should be able to distribute the wheel point load fairly well.
The live load is not generally used to help resit sliding and overturning. I thought AASHTO stated this somewhere.
However, I'm pretty sure it can be used in impact design though.
EIT
www.HowToEngineer.com
RE: AASHTO requirement for wheel setback from wall
If he signs and seals, and the county signs off, and the owner is ok, its on him then to design correct. usually the wall would be at least 2'-0" tall to meet any impact requirements.