Determining Appropriate Load Area for Forklift Operations on Concrete Deck 2

[mason2023]

I need advice on a specific load calculation for a project. Our task involves using a forklift (8000 pounds) on a 10-inch concrete deck, designed for a maximum live load of 75 psf. The deck is supported by 24-inch wide by 30-inch deep concrete beams, spaced 18 feet 8 inches apart, and foundation walls about 25 feet apart.

The question is: Should the live load of the forklift be calculated based on the tire contact area (10" x 10" per tire, 4 tires) or the forklift's overall footprint (5' x 3') or something else entirely (does the load spread at all as it travels down through the concrete?)? It is fairly equipment agnostic and a forklift is only one piece of equipment that we are considering.

This decision will impact the safety and feasibility of using a forklift or another piece of equipment on the deck. Your expertise on which area to use for accurate load calculations would be greatly appreciated.

 

[mason2023]

@XR250 - lol, hopefully not in this case!

@Bridgesmith - unfortunately my route to the stones runs perpendicular to the beams so I won't be able to utilize them as a path. Your point about damage vs failure is a good one, especially since this slab will be removed anyway.

@enable - Unfortunately, I have to reuse these stones later so I can't break them up into smaller pieces. Otherwise, you and I are very much on the same page. Especially your point #5.

 

[SlideRuleEra]

mason2023 - Putting together input from XR250, Bridgesmith, and Enable you have what I consider to be the answer about what to do and the basic reason why, that is:

Assume that use of an 8000 lb. (or heavier) forklift carrying a 5000 lb load is unacceptable... because the machine puts a 13,000 lb. point load anywhere on the slab... with the worst place being at the center of the slab.

I was taught long ago (before handheld calculators or readily available computers) that when facing a problem I don't know how to work, draw it to scale. The "big picture" is worth a thousand words... to help me understand what is going on and what reasonable simplifying assumptions can be made:

To me, what "jumps out" of the sketch is that the forklift is "small" compared to size of the elevated slab.
Footprint or tire loading of the forklift are trivial details. Assuming a 13,000 point load for a loaded forklift is reasonable. This makes the problem a whole lot simpler mathematically. This is NOT an issue of how the load is applied to the slab; it concerns a 13,000 point load collapsing the entire slab. I can show you what other simplifying assumptions I would make to get an (approximate) answer that screams "Don't Put That Forklift On The Slab"... but in my opinion you have the answer already.

 

[lexpatrie]

If this is being bid, isn't there a mechanism to ask this question as part of the procurement process? I mean it would put all bidders on an even footing, and perhaps that's not the goal for a GC bidding the project, but..... I mean, I see your point, if you bid it with the forklift and others are using handcarts and wheelbarrows your bid might be lower, but you can't be sure it'll work because you have to get the engineering done after the fact, provided you win the bid.

This isn't the construction you seem to have, but the document gets fairly involved and some of this should apply.

https://steeljoist.org/wp-content/uploads/SJI_Steel-Deck-Webinar_FINAL_03_19_2018_1_handout.pdf

Regards,
Brian