Forklift on Elevated Slabs

[ma3355]

I am currently working on a project where most of the structure is made out of concrete. this Week i encountered a unforeseen problem. the EOR asked me submit the type of equipment that i was planning to use on the elevated slabs. i used a Forklift Caterpillar P5000 pneumatic on many occasions without any problems. but this type, the EOR told me that i was not allow to use this particular machine because it will exceed the Max Point Load of 3000 lbs.

this is some of the specs about the forklift:

* Front Wheel Axle with rate load = 11570 lbs.
* the tires contact area is 7.5" X 2.5"
* Stress will equal to 309 PSI per tire

i want to contest his response, but my question is the following? Do i use this force as i uniform distributed load or do assumed a point load?

**** thi is the response by the EOR:

"The garage levels are required to be design for 40 psf and a max point load of 3000 lb (see below code reference). This lift with a full load would exert a point load nearing 6000 lbs. So Therefore it is not acceptable to use this equipment."

Thanks,
Mauricio

 

[JAE]

You would have to analyze this with the point loads in various places on the slab to see what the effect on shears and moments would be.

If you don't know how to do this you would probably need to hire a structural engineer to check the floor and provide the EOR with a report on the findings, and possibly share with the EOR the calculations to back it up.

The 3000 lb. load is probably a standard value based on the live load table from the IBC or whatever code is applicable. I don't know for sure but the EOR probably didn't do any significant calculations for the 3000 lb. point load so this may not really be the true limit.

I would ask the EOR whether another engineer's calculations would be acceptable if they showed that the wheel loads work.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[JAE]

...and having said all that, I don't know the nature of the slab so the EOR may also know by simple observation that a 6 kip load won't work.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[hokie66]

If this forklift is operating on a carparking floor, designed for 40 psf live load, I agree with the EOR. I assume you are a contractor. If you want to contest the decision, you should hire your own engineer, who may or may not find reason to support your position. I doubt it is worth the time and expense.

 

[Ron]

Agree with hokie66 and JAE....hire an engineer. Forklifts impose high point loads and the EOR is correct in initially rejecting the use of this equipment unless you can clearly prove otherwise. Each structure must be evaluated on its own merits. Just because you've used this equipment in the past doesn't mean it will work on this structure.

 

[ma3355]

thanks everyone for your responses! my background is in structural (concrete mostly) and i do plan-review, consulting, and placement shop drawings for a Contractor. i know that there are other factors that have to be taken into consideration (i.g. strength of the concrete, reinforcement, thickness of the slab, etc.)

i do agreed with all of you... having an outside engineer to do the moment and shear design calculations will be counterproductive! i know that EOR used table 1607.1 from the IBC to get this number of 3000 lbs and 40 psf. but i was thinking of this as a uniform load instead of a point load. please advise if my assertion is correct.

Thanks,

 

[JedClampett]

Forklifts are one of the reasons for concentrated loads. You have a small, hard tire with a very big load. It can't be simulated as a distributed load. I don't understand your statement:
Maybe you meant productive or don't know what counterproductive means. But you should hire another engineer to evaluate the forklift use. You and/or your boss should want maximum protection if he's going to run a forklift pver a floor that the EOR has prohibited this use of. You don't want that forklift damaging the building or killing someone.

 

[hokie66]

I think to him "counterproductive" means "expensive".

 

[DETstru]

Let's not even consider the point load for a moment. Since we only have front axle load, I'm going to assume the entire loaded truck weighs about 13,000# fully loaded.

The garage floor was designed for 40 psf. It's a parking garage so they're not usually given much extra capacity. You would need 325 square feet of floor area to support your lift, assuming nothing else is within that area. I don't know what the framing plan looks like, but it's very possible that you don't even have a single member with 325 square feet of tributary area. You'd be taking the entire capacity of that member and placing it in one location, this would easily exceed the design load before even considering point loads.

I admit I'm making some very big assumptions here but it is a possible scenario depending on the framing plan.

 

[msquared48]

Be careful in the analysis and be conservative. I just looked at a loading dock area that is failing - concrete cracking up along a line of support. This a concrete infill over metal deck supported at 4 foot centers with CMU infill walls over a PT slab (Loading dock is built-up over the PT). Sees semis with trailers - HS20 and 25 loadings. Building is only about 12 years old.

Mike McCann, PE, SE (WA)

 

[JedClampett]

msquared48, the OP checked out long ago when our answers didn't give him permission to drive the forklift in the building.

 

[msquared48]

Musta been around the same time I told another client the same thing for the first floor of an old JC Penny Building.

Mike McCann, PE, SE (WA)