Loading Pad Design
Loading Pad Design
(OP)
Does anybody know of a good reference material for the deisn of a concrete loading pad that can handle the weight of a fully loaded tractor trailer. What would the design load be?
I am considering an 8" thick or perhaps a 9" thick concrete slab and about 60' to 70' long but need to design the reinforcements. Also, what kind of joint material to use in between the slabs.
Thanks,
I am considering an 8" thick or perhaps a 9" thick concrete slab and about 60' to 70' long but need to design the reinforcements. Also, what kind of joint material to use in between the slabs.
Thanks,






RE: Loading Pad Design
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The soil supporting the concrete is more important than the concrete itself. For good soil, properly prepared, 6" of concrete with no reinforcement is more than enough. For poor soils, your proposal, "filled" with rebar is most likely inadequate.
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RE: Loading Pad Design
Then you need to consider the concrete mix design for strength and durability. This is a fairly high abrasion application with lots of loaded twisting and turning. The surface durability must be good.
For thickness design, the PCA Pavement design method is good or you may use the AASHTO Rigid Pavement design procedures. The PCA method is a bit more rigorous and accounts for a few more parameters (radius of loading, edge considerations, etc.).
The layered elastic approach is also good as long as you know and understand the elastic properties of the concrete and the subgrade, and apply them properly in the analysis.
In general, semi-trailer loading areas will have concrete thicknesses in the range of 7 to 9 inches. Be sure to put strong controls on the flatness of the subgrade and thickness control of the concrete as these contribute significantly to crack potential.
All joints should provide load transfer, whether through a key design or by dowels. Be careful with doweling in two directions to intersect at joints....causes cracking. For these applications I would dowel the joints perpendicular to the traffic and key the joints parallel to the traffic.
Use the largest aggregate practicable as this will reduce shrinkage and provide better load transfer across saw-cut control joints. I would not use concrete with a nominal coarse aggregate size smaller than No. 57 stone.
RE: Loading Pad Design
RE: Loading Pad Design
Dik
RE: Loading Pad Design
RE: Loading Pad Design
As far as the soil goes, the client claims he has good sand and may not go for a full fledge boring. I said that I'll base my work on 2 tsf bearing and it will be his responsibility to verify. Is there a quick way of sizing the pavement and the required rebars?
RE: Loading Pad Design
Find out the use frequency of the ramp and then design according to either the AASHTO method or the PCA method. Either will yield a pavement thickness that will likely be in the 6.5 to 8 inch range.
Again, make sure you put a lot of quality criteria in the concrete mix. Don't just let them drop some ready-mix in a hole.
RE: Loading Pad Design
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RE: Loading Pad Design