Slab-on-Grade Thickness in High Seismic Areas
Slab-on-Grade Thickness in High Seismic Areas
(OP)
Based on the parameters below, would anyone see the need to increase slab-on-grade thickness from 4" to something thicker:
- Seismic Design Category= D
- Live load= 150 PSF (IMPORTANT: there are NO significant point loads acting on the slab)
- Modulus of subgrade reaction= 280 psi/in.
- Geotechnical report recommends conventional floating slab-on-grade
What I'm trying to get at is this: based on the above, why even consider thickening the slab? In my office there is this notion that if the Seismic Design Category is D (or worse) that you automatically bump up the slab thickness. I have scoured the ACI standards and the internet (including this forum) for such justification and I'm coming up with nothing! In this scenario,adding thickness to the slab I feel is adding unnecessary cost and material.
Any input would be appreciated.
Thanks
Danny
- Seismic Design Category= D
- Live load= 150 PSF (IMPORTANT: there are NO significant point loads acting on the slab)
- Modulus of subgrade reaction= 280 psi/in.
- Geotechnical report recommends conventional floating slab-on-grade
What I'm trying to get at is this: based on the above, why even consider thickening the slab? In my office there is this notion that if the Seismic Design Category is D (or worse) that you automatically bump up the slab thickness. I have scoured the ACI standards and the internet (including this forum) for such justification and I'm coming up with nothing! In this scenario,adding thickness to the slab I feel is adding unnecessary cost and material.
Any input would be appreciated.
Thanks
Danny






RE: Slab-on-Grade Thickness in High Seismic Areas
RE: Slab-on-Grade Thickness in High Seismic Areas
One important piece of information I left out is this: in the geotechnical report they do state that differential settlement could approach 2" however this does not specifically point out that the slab will settle differentially.
Thanks again.
RE: Slab-on-Grade Thickness in High Seismic Areas
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Slab-on-Grade Thickness in High Seismic Areas
RE: Slab-on-Grade Thickness in High Seismic Areas
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.