Slab on grade for office building 1

[timathy]

I've typically used 5" reinforced slabs on grade for all lightly loaded commercial structures (offices, etc. No rack loading, forklifts, trucks, etc.)

I'm looking at a set of drawings that specifies 4" for this same type of condition. I've looked around for guidance as to whether there is a recommended thickness for a lightly loaded slab, but apparently my google-fu is lacking. Lots of information for heavily loaded slabs, of course.

The 4" doesn't seem wrong - just different. Does that thin of a slab generally have a problem with curling?

What are you used to using and do you have a reference material that you can point to?

 

[Bagman2524]

ACI-360 - Design of slbas on grade. Curling would depend on the overall plan dimensions of the slab

 

[strucguy]

I worked in mid-west and north-east and 4" thick slab on grade for office buildings is pretty common in both the areas.

 

[JAE]

This attachment is from an old CRSI table for Slabs on Grade.

 

[chrislsnider]

Thanks JAE - I've been looking for something like this too.

 

[RHTPE]

I've always felt that the thinner the slab on grade, the more important precision in base prep becomes. The skill of the sub preparing the base should be considered, as variations in the base elevations impact thinner slabs more adversely.

Ralph
Structures Consulting
Northeast USA

 

[Ron]

RHTPE is exactly right. For a 4" slab on grade, ACI gives a tolerance of -1/4", +3/8". That means that the subgrade preparation has to be on target and the sawcut joints have to be done quickly and correctly.

 

[msquared48]

What do you mean "old" JAE? That's the same one I use!

Mike McCann
MMC Engineering

 

[Archie264]

Me too.

 

[JAE]

Long in the tooth?