AASHTO H-20, HS-20. . .
AASHTO H-20, HS-20. . .
(OP)
I am trying to design a box culvert cover to be traffic rated and heelproof. For the heelproof, I have found that a gap of 1/4" or less will meet the local standards. The "traffic rated" part has me concerned. I have looked at many manufacturers of grating and all will supply me a grate that is H-20 rated. When I ask (out of my own curiosity) what the actual loading is for H-20 in psi or load over area, they all say that it is based on a 32k axle. This does not tell me what the actual loading is. Is there a call out for the loading of one tire? What is the size of that tire in contact with the grate? I have searched the internet and have found nothing stating the tire size and tire load.





RE: AASHTO H-20, HS-20. . .
The tire contact area for HS 20-44 shall be assumed as a rectangle with a length in the direction of traffic of 10 inches, and a width of tire of 20 inches.
Therefore, the pressure would appear to be equal to 16 kips / (10" x 20") = 80 psi or 11.5 ksf. In case you need to know, these two tires on the axle are spaced six feet apart (center-to-center) transverse to the direction of traffic and the successive axles of an HS truck are 14 feet apart along the direction of traffic.
Good Luck.
RE: AASHTO H-20, HS-20. . .
RE: AASHTO H-20, HS-20. . .
RE: AASHTO H-20, HS-20. . .
RE: AASHTO H-20, HS-20. . .
RE: AASHTO H-20, HS-20. . .
The reason for this is that I am very suspicious of the supplier. The design calls for 2-16"wide x60long" grated areas (1 in each lane) to drain directly through the top of the culvert to the waterway below. The supplier showed me a sample grate that was only 3/4" thick and said that it was rated for traffic loads.
I want to know what parameters that I can use to test these grates so that I know I am not putting grates in traffic lanes that will fail. The final dimensions of the grates are 16" wide x 20" long. They are resting on a frame that is poured into the culvert top.