Dowels to Transfer Large Wheel Loads
Dowels to Transfer Large Wheel Loads
(OP)
I've got a new concrete ramp that needs to be tied into an existing building slab. The problem is this vehicle produces wheel loads of 100kips on a 3'x3' contact area. Can any reasonable amount of dowels be sufficient to transfer these massive wheel loads into the existing slab? We considered cutting back into the existing slab to create an inclined surface for the connection, have shear friction and some amount of concrete bearing help transfer the loads. We then realized however that the end of the existing slab is heavily reinforced and decided against it.
Any ideas would be greatly appreciated.
Any ideas would be greatly appreciated.






RE: Dowels to Transfer Large Wheel Loads
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Dowels to Transfer Large Wheel Loads
RE: Dowels to Transfer Large Wheel Loads
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Dowels to Transfer Large Wheel Loads
RE: Dowels to Transfer Large Wheel Loads
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Dowels to Transfer Large Wheel Loads
See a google image search for "dowel bar placement" to see what is often done.
RE: Dowels to Transfer Large Wheel Loads
RE: Dowels to Transfer Large Wheel Loads
Have you been driving these same wheel loads over the edge of the existing slab, with no ill effects? There is a concrete cutting device (cutting equipment, water cooled) which looks much like a chain saw, with a bar and diamond impregnated chain for cutting the conc. At about the same elevation that you show your dowels, I would plunge this into the existing slab edge about 4 - 5", btwn. the #4 ties @ 8" which run up the face/edge of the existing slab. These slots in the existing slab get a 8 or 10" long steel bar which fits the cut slot. These are your shear mechanisms and distribute/tolerate much more shear than a round dowel will. Pavement designers (DOT’s., etc.) are using these shear plates instead of dowels at pavement joints for this very reason. You will also need some dowels in tension to tie the two slabs together. Then the controlling shear cap’y. becomes what the bottom half height of the existing slab edge, plus the #4 ties @ 8" will allow, as some sort of a corner break-off (break-out) load. In the new ramp slab, you should also extend/turn the rebars, shown in side view, down as ties at the edge of this new slab, on either side of each of the new shear bars. Check this new slab and ties just as for the existing slab, as mentioned above. Tool the top of the joint and fill it with a proper joint filler/sealer system. Then try your high strength grout, but I don’t have much hope of that lasting long. It might get moved and broken up by the wheel loadings.
RE: Dowels to Transfer Large Wheel Loads
You loading configuration is strange. What is it? 100kips is a high load, typical of an industrial application; however, the "footprint" you gave is quite large.....if your info is correct, this indicates that your load transfer is likely less critical than you might think.
Another issue here is that you are planning to use bonded dowels across a dynamic joint. Generally not a good idea. One side of the dowel should slip. Cracks will develop at the ends of bonded dowels. If you are concerned about the sloped slab sliding down, you can put a thrust block at the bottom of the slope to prevent that.
I don't have any capability to do a sketch right now, but will attach one when I get back to my office.
Please provide additional info on what is loading the slabs.
RE: Dowels to Transfer Large Wheel Loads
Thaidavid
RE: Dowels to Transfer Large Wheel Loads
RE: Dowels to Transfer Large Wheel Loads
I'm curious about the 3:1 chamfered edge on the existing slab. Do you know why it was constructed this way? Is the existing slab part of a building? The way it's reinforced at the edge looks like the slab may be integral with a grade beam.
RE: Dowels to Transfer Large Wheel Loads
RE: Dowels to Transfer Large Wheel Loads
i've seen this concept used at the edge of a concrete hardstand for heavy aircraft. The asphalt leading up to it would form ruts in the wheel path, exposing the concrete edge (if not ramped) which would be an unpleasant bump.