Rack slab design - ACI 318 vs ACI 360

[BAGW]

Hi,

I have racks inside the building. They are pretty tall. Close to 60'-0". Similar to ones in HomeDepot.

The racks will be supported off slab on grade. The rack posts are spaced 4'-0" x 4'-0" and the maximum post reaction is 20kips.

What code am I supposed to use for the slab design? can I stick to ACI-360 slab on grade design? Or I am forced to use ACI 318 for such structures.

 

[driftLimiter]

318 is the code, 360 is a guide. 360 contains much more information specific to slab on grade and warehouse pallet racking as well as other considerations such as flatness tolerances that you need to consider.

 

[HTURKAK]

They are pretty tall. Close to 60'-0". Similar to ones in HomeDepot.

My concern would be differential settlement of the racks due to incompetent soil rather than design of the SOG foundation.
My points and suggestions ;
- I would develop FEM model supported on Winkler springs and check for bending and punching as per ACI 318.
- If the rack layout is frozen, i would design the roof and walls supported by rack structural system .( afaik , called silo system )

EDIT:
ACI 318 -19 Relevant Clauses for STRUCTURAL slab on ground;

13.2.4 Slabs-on-ground
13.2.4.1 Slabs-on-ground that transmit vertical loads or lateral forces from other parts of the structure to the ground
shall be designed and detailed in accordance with applicable provisions of this Code.
13.2.4.2 Slabs-on-ground that transmit lateral forces as part of the seismic-force-resisting system shall be designed
in accordance with 18.13.

If the rack ht 60ft and the point load 20 kips, i would consider structural slab on ground found. and follow ACI 318 code rather than ACI 360R which is guide report and could be informative for this case.

 

[JAE]

ACI 318 specifically excludes design of slabs-on-grade.

 

[bones206]

Check this article: https://issuu.com/structuremag/docs/january_2024/24?ff

This approach considers seismic rack overturning as the governing case for slab thickness design.

 

[human909]

While I've rarely done much industrial slab of grade design. I find this guide super easy to digest.

https://ccaa.com.au/common/Uploaded%20files/CCAA/Publications/Technical%20Guides/INDUSTRY_GUIDE_T48_Guide_to_Industrial_Floors_and_Pavements_Design_Construction_and_Specification.pdf

It may be useless to you as it uses different units and codes. However in the end the physics and engineering is the same.