Asshto HL-93 loading

[dicksewerrat]

I am trying to find out what HL-93 loading really is. If it is an HS-20 truck on top of a concrete slab, wouldn't the slab have to take some of the load by deforming before the load would be transfered to the soil? And wouldn't the contact area be the area of the slab?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[Qshake]

Hi dicksewerrat - I suppose you're inquiring about a condition where the slab is supported by walls or piling and the interior is filled with soil. In this case, yes, the slab must deform a certain amount to impart load to soil beneath it. In the case of slab on grade that's not the case. This isn't very clear in your post.

The contact area would be proportional to the deflected or influenced area of the slab making contact with the soil. If the deflection is small the contact area on the soil is small.

I hope this helps.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[dicksewerrat]

Thanks Qshake. This is a highway load on buried pipe. But not all highways are concrete slabs. We have flexible pavements also, so I am having trouble accepting this for all highway. My best idea would be to go to an HS-25 rather than HS-20. Then they say that below 8 feet there is no live load. Can't figure out the DOT thought process on this.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com