H-20 Plate Design
H-20 Plate Design
(OP)
I need to design a plate inside a private business that is to go above a drainage pit. The plate is required to be designed for H-20 loading. I have an old formula in my notes that is as follows Moment = 0.5(S+2). This formula will give the required moment strength of the plate in ft-kips/ft and I believe is came from an old AASHTO code. Is this the correct formula to be using? FYI, my pit width is 4'-0"






RE: H-20 Plate Design
RE: H-20 Plate Design
I agree with WARose; 3/4" should be fine for strength. IN NYC, contractors typically use 1" or more for plating because the City has a 3/4" deflection limit.
RE: H-20 Plate Design
It is a formula for concrete slabs that can be found in ASSHTO but I don't see how it wouldn't apply here. I ended up finding the formula in AASHTO (17th edition equation 3-15). The equation was reduced from what is given in AASHTO.
Using this formula I calculated a required thickness of .78 inches. I was going to round it up to 1-1/4" but decided to go with 1" thick. It's good to hear that I am at least in the ballpark and slightly heavy for strength.
One issue I have is that the pit cover is made up of two 6' long plates and a 4' section of grating. So I have a free edge on the plate. I didn't like that so I put a 6x4 tube on the free end to support the load as it transfers from the grating to the plate
RE: H-20 Plate Design