Compact excavator on floor slab

[dakota99]

One of my contractors wants to drive a compact excavator on the second and third floor of a building to help him with some of the rnovations. The unit weighs 3500lbs and rides on a set of rubber tracks that are about 4' long and 10" wide each. The floor construction is 3" formed conc. floor that sits on joist 24" apart. The floor joist look like they should handle the contruction load, but I'm not sure how to distribute the load onto the slab to replicate a realistic condition. My first approach was to use half of the excavator weight add 20% for impact loads and put that load on a 12" wide segmet of floor and analyze it as a one way slab. The slab failed under those load conditions, but I think that I might be too conservative in my approach. If anyone has any suggestions or have ran into a similar situation, I would like to hear from you.

 

[SlideRuleEra]

At various times, I have addressed this type situation (Contractor wants to do something "unusual") from all three sides of the question - Contractor, Engineer, Owner's Representative. This is the best way that I know of to deal with it:

Tell the Contractor that if he wants to this, he (the Contractor) should hire (at his expense) an independent Engineer to investigate and prepare a (detailed) plan of action, and submit a signed, sealed report to you with his (specific) recommendations. You review it, and if you agree, accept it. Make the Contractor comply with it exactly.

I know that this sound like a bureaucratic solution, but the results are surprising. When the Contractor finds out that he will be responsible for the engineering costs, consequential damages, etc. (instead of you), most of the time, he "suddenly" finds a more conventional solution that works just fine.

On the occasions where the Contractor submits an acceptable plan, the result is a very clever, cost-effective approach.

Best Wishes

http://www.SlideRuleEra.net

 

[Lutfi]

I second SlideRuleEra's input and thoughts.

Lutfi

http://www.cdeco.com

 

[AggieYank]

dakota99.

the method of analyzing it is exactly what I would have done. In fact, I would have been less conservative, using more load for impact load (maybe 25-50%).

In this case however, my advice is to tell him that is a means and methods thing, and if he wants to do it, you are in no way responsible. If he is worried about the engineering aspect, he'll need to hire someone to investigate it.