Vehicle Loads

[weeber]

I need information for vehicle loads that I can't seem to get a straight answer for. I am involved in the design of concrete pad at a plant site that will be subject to infrequent vehicle loads. The vehicles that will be driving on this pad will be pickup trucks, large forklifts and small cranes for access to a pipe rack.

I'm assuming that the crane will be the heaviest piece of equipment, but I'm finding wildly varying weights for cranes. I do not have any specific information as to make or model of the cranes that might be used. Does anyone have a rule of thumb for vehicle loads that would fit this scenario?

 

[JedClampett]

If the cranes are travelling over public roads (they are not limited to the plant site) they shouldn't create more than a H-20 load. If they were larger than H-20, all bridges, culverts and pavement they travel over to get to the site would have to be checked.
If the cranes are unloaded when they pass over the slab, I'd check for an AASHTO H-20 load. If they're loaded, you'll have to logically limit the type of crane and capacity that can travel over the slab.

 

[jheidt2543]

While the crane might be the heaviest total load, my thought would be that the forklift wheel loads may have the highest concendtrated load when it makes a material lift, particularly if the forktruck is the solid wheel type.

 

[SlideRuleEra]

weeber - For an industrial facility - a rule of thumb is probably the best way to go. To keep electric generating stations operational, I have seen carefully specified design criteria ignored by the personnel who are responsible for "keeping the lights on" - and rightfully so. For example, a truck crane may have to make a heavy lift at maximum radius - then the point load from one of it's outriggers is much higher than expected - this can happen ANYWHERE on a plant site - not just in expected locations. We have found the best solution is to use high quality, well compacted subgrade material - make it quite thick. Then 6 to 8 inches of concrete with one layer of rebar, to tie everything together.

For areas that are used (abused?) for heavy duty bulk material handling, 12 inch slabs with two mats of rebar (placed on the quality subgrade described above) seem to be able to take anything that plant operations can dish out.