While transporting the crane on the slab; from my experience, the pressure at the surface of the concrete is equal to the tire pressure….that one threw me off a bit when I first heard it but if you think about that it makes sense. The heavier the crane is, the more the tires will bulge and spread out the load. Generally your tires under the counterweights take the most weight, so just treat the carrier frame like a beam and solve the best you can with each axle acting as a pin support.
Solving loading conditions under an outrigger is more complicated. However, a great way we got out of determining this was we placed the entire weight of the crane + weight of object + weight of rigging on one outrigger, and calculated the loading by a 4’ x 8’ oak timber (we usually used 12” thick oak timbers). This is conservative, but if it exceeded the concrete’s strength………a great source of reference is “Cranes and Derricks” by Shapiro. It lays out the required formulas regarding C.G. of the boom, etc., that is needed to accurately solve your problem. But it will take some time and you may not be able to get all the info you are wanting.
One last thing, in the book it talks about the effective length of your oak mats. This basically deducts the amount of area your able to spread out the load….if you have a 4’ x 8’ mat, the effective area could be say 4’ x 6.5’.
