Composite Metal deck design 2

[vic4f]

I am designing composite metal/concrete floor with beam supports. The floor will serve as a warehouse and have a forklift running on it. I have looked every where to find what a reasonable impact factor I should add to the forklift for design purposes. The forklift is about 12,000 lbs fully loaded. I am thinking that between 10% to 25% would be a reasonable impact factor. Is this reasonable or is there some where in IBC or somewhere else I can find the impact factor for a forklift?

 

[Taro]

Composite metal deck slabs are usually not recommended for vibratory or dynamic loading such as forklift traffic. This type of loading can cause the topping to debond from the metal deck and lose composite action. In such cases, the deck is used as a stay-in-place form and the concrete slab is conventionally reinforced with rebar to carry the entire load without any contribution from the deck. Check with the deck manufacturer to see what they recommend.

I would also use a larger impact factor. Something in the range of 1.5 to 2.0. That is not taken from a code, but just based on my engineering judgment. Elevator supports are designed for a factor of 2.0. Forklifts do not have the entire load starting and stopping vertically like an elevator, but it is similar.

 

[jike]

I agree with Taro, composite metal deck should absolutely not be used for a slab designed for forklift. You, however, can use metal form deck for forming the slab and then have two layers of rebar (top and bottom) in each direction.

Make sure you design the rebar for positive moment, negative moment and bottom distribution steel. Design your slab for the following conditions:

1) two loaded forklifts passing in an aisle. Arrange the trucks in both directions, since either may control.
2) one loaded forklift stacking adjacent to a fully loaded floor.

I typically have used 30% impact. This corresponds to impact recommended by AASHTO for vehicles on short span bridges.

 

[csd72]

viv4f,

This sounds like something that really should be designed by a structural engineer - we are cheap compared to you mech. guys.

For example - have you considered the effects of point loads on your slab?

 

[vic4f]

All

Thanks for your valuable input. I did not fully discuss the composite conc/metal deck approach I am taking. I agree with the suggestion of using the metal deck as a form and not use it in the design of the slab and this is my approach for the slab. I am also designing for both positive and negative moments for the slab and checking the shear on the design. Again, you all for your input

Regards

 

[csd72]

vic4f,

That is not what I meant. Do you know what effective width you need to take for design?