Get yourself some copies of the PCA design guidelines for concentrated loads on slabs on grade.
D. Matthew Stuart, P.E., S.E., F.ASCE, SECB
Senior Project Manager
Structural Department
Associate
CMX
200 Route 9
Manalapan, NJ 07726
732-577-9000 (Ext. 1285)
908-309-8657 (Cell)
732-298-9441 (Fax)
mstuart@CMXEngineering.com
-----Original Message-----
From: Jeff Hedman [mailto:jeff_h@lrpope.com]
Sent: Thursday, August 28, 2008 11:20 AM
To: seaint@seaint.org
Subject: Slab effective area for point loads
I am currently working on a tenant improvement where the client wants to add a mezzanine. The lateral analysis is done, however, since the majority of the mezzanine will be used as storage, I am getting some large point loads on the existing slab on grade. I could just make them cut some footings everywhere, but some loads are small enough that the punching shear works out, but as far as flexure is concerned how large is my effective slab area that I can use for ‘footing’ calculations to determine if the slab can take the point load. The slab is only 4” thick with #3 bars @ 18” o.c. so I am not expecting too much, I just want to establish a threshold for when I need to have a footing installed.
Jeff Hedman