Crane Load on Pavement

[geomane]

We are designing a pavement section for a new parking lot. After the pavement section is constructed, it will be subjected to crane loading with an applied pressure at the outrigger of 71 ksf. The outrigger has a bearing area of 1.5ft x 1.5ft. The client wants flexible pavement.

I don't see how any flexible pavement section could support that crane loading without a shear failure. Outrigger pads/cribbing will have to be used to reduce the bearing pressure. Anyone have experience designing pavement sections with similar loading conditions?

If we could convince the client to use a rigid pavement, would the strength then just be controlled by the modulus of rupture of the concrete?

 

[PEinc]

The person responsible for using the crane needs to design outrigger cribbing that will reduce the pressure on the paving to an acceptable limit. Cribbing could easily be 8'x8' or larger. Crane companies have various sized crane mats that are routinely used. Require a signed and sealed crane mat/cribbing design. Remember, a large, street legal truck could have a 32 kip axle load with 4 tires. Two tires could bear on an area of about 1.5' x 1.5' = 16 kips / 2.25 sf = 7 ksf. 71 kips / 7 ksf = 10.1 sf = 3.2' x 3.2' which is a very small amount of cribbing area. I would not design a more expensive, rigid pavement just because someone need to use a crane occasionally.

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