Forklift Load on Structural Floor 3

[On S. H.]

thread507-122331

I would be grateful if Engineer jike could kindly enlighten me on how to design for the bottom distribution steel of a concrete slab (that is subjected to concentrated loads due to forklift truck) which has been stated to be significantly larger than the normal temperature steel in Engineer jike's comments at the above forum on 26 Apr 2005 17:06 as shown in the attached screenshot.

FYI, I always thought that for a one-way structural slab, its bottom distribution steel shall be the normal temperature steel as specified in the reinforced concrete design codes.

Thank you.

Regards,
On S. H.

 

[jayrod12]

Because you want the bottom steel in the weak direction to promote load spread to a larger width of primary steel. Otherwise you would likely end up needing significantly more primary bottom steel.

 

[BridgeSmith]

In the AASHTO bridge design spec (LRFD Section 9.7.3.2), the required area of distribution steel for concrete decks, is calculated as a percentage of the primary reinforcement area using the formula 220 / sqrt S, with a max of 67%, where S is the effective length of the primary span in feet. Since for our bridges, the primary span for the deck is between girders that are typically 8-9 feet apart, we're always at the 67%.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[JLNJ]

The steel deck institute has a design methodology for the distribution of concentrated loads on an elevated slab.

Usually, the shear at the support controls. I'd start there first since it may well control your slab depth.

 

[dik]

Unless things have changed, most deck manufacturers do not recommend forklifts and steel deck together.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[On S. H.]

Many thanks to the above structural engineers for your advice.

 

[JLNJ]

I think what dik is getting at is in the notes at the bottom of most composite deck catalogs. The deck manufacturers don't stand by those high tabulated values where there is a chance that the loads are either cyclical or brought on my impact. The little nubs which create the composite action are not "toothed" in particularly well and could break down over time.

I don't think there is anything wrong with using steel deck as a form, but the heavy wheel loads from a fork truck are going to require a pretty thick slab.

 

[dik]

JLNJ... I knew there was a reason for looking at the 'fine print'. I've used it often as a form... but, that's it.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik