×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Surcharge transfer from SOG to footing

Surcharge transfer from SOG to footing

Surcharge transfer from SOG to footing

(OP)
I have a floating slab on the interior of a large commercial building.  The slab is 5 1/2" and supports storage racks weighing as much as 3500 lbs and forklift traffic.  The location of the storage racks is to be determined after the project has started.  The slab bears approximately 1'-0" above the column footing and is not attached to the column footing (no dowels).

Does the slab live load or dead load need to be applied to the interior column footing as a surcharge load?  I cannot find anything that gives recommendations for this condition.  Everything I find applies to retaining walls.  Any recommendations or code references would be appreciated.  Thanks in advance.

RE: Surcharge transfer from SOG to footing

While I don't have any code references that require the load to be transmitted to the footing, just thinking about the mechanics of the slab load being applied to the bearing strata below makes me believe that the load will be transmitted to the footing through the soil between the footing and the slab.  Even if the load transmits out at a 45 degree angle from the slab, some addtional stress will be placed on the footing.  As a general rule, I always analyze footings below slabs with the slab dead and live applied to them.

RE: Surcharge transfer from SOG to footing

Yes, but the influence area is sometimes difficult to assess.  Unless the load is close to the column, it won't have much effect for a slab on grade, since most of the load, unless truly uniform across the slab, goes through the slab in shear and the shear plane is very near the load.

RE: Surcharge transfer from SOG to footing

Once you get down to the bottom of the footing, depending on the thickness of the footing, the additional load from any rack leg will only be in the range of 200 to 300 psf considering the spreading Ron mentioned.  This should not be a deal breaker for the soil structure.  

As for the forklift load, this is intermittent, and may not even be present depending on how close the forklift can get, or needs to get to the column.

Just use your judgement here.

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
 

RE: Surcharge transfer from SOG to footing

(OP)
Thanks for your help.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources