Point Loads on Concrete Pad Vibration Isolators

[hankvol]

I am a mechanical engineer being thrusted into the middle of a 4 year old project. We have a 6ftx8ftx8in concrete pad which is supported 100% off the ground by 8 spring vibration isolators. A 5000 lb fan sits on the slab. The question is if there is an "easy" way to ESTIMATE the loads on each of the spring isolators. I thought taking the total weight of pad and fan and dividing by 8, but the isolators are not symmetrically placed around the pad. In addition the fan is located off the centerlines of the pad. Any help would be appreciated.

 

[civilperson]

Do you know how to calculate the centroid of the springs? The distance of the centroid of the mass to the centroid of the springs is the eccentricity and from the eccentricity you can calculate the weight on each spring? (Can be indeterminate or have many correct solutions.)

 

[tngolfer]

Civilperson is right. This is just a statics problem. Due to the large number of springs, it will definitely be indeterminate. If you have access to a structural analysis program (RISA, etc.), you could use that. You may want to design the spring for a higher load than your analysis comes up with in case the fan or supports are not exactly where you analyzed them to be.