Calculating Concrete slab bending stress

[mwall744]

I'm trying to calculate the bending stress on a concrete floor slab due to a force of 31000N 1m above the floor. The slab size is 6 in. thick by 16 ft by 8 ft wide.

Does anyone have any advice on the best way to go about this simple calculation?

Can I assume that it is simply supported (because it is on the ground over a foundation?)

Thanks for the help!

 

[kslee1000]

Depends on the nature of the concentrate load, it might have some lateral distribution width, "b". The simplest way is to design a one way beam (slab) with width b, and spanning in the other direction. Then place the concentrate load as point load. Note, it might be possible to distribute the concentrate load both ways for certain type of loadings, such as a wheel load, the concept is the same. Otherwise, use FE program to find out exact solutions.

 

[mwall744]

Thanks for the quick reply! I realize I was not very clear though...

The force is applied parallel to the floor (or in the x/y-direction, which creates a moment, which then leads to the bending stress. For example, a robot on a 1 m pedestal. If the robot produces a 3000 N force in the x-direction, how should I calculate the bending stress in the slab/beam?

Thanks again!

 

[kslee1000]

How about post a sketch with coordinate system marked? It will help.

 

[Ron]

You can treat it as a pedestal footing...with a rather large base.

 

[mwall744]

Here is a diagram...

http://files.engineering.com/getfil...bb2-b500-339c5396db1e&file=Stress_diagram.doc

 

[kslee1000]

What is the edge support condition - all sides rigidily/simply supported; two long/short sides rigidily/simply supported, or any other combinations?

And what is the accuracy you are looking for - approximation vs exact?

 

[kslee1000]

Before you go through all the troubles to answer those question above, assume you can live with approximation, and know how to handle boundary conditions, then you may simply replace the concentrate load with the moment (M=F*h) in the method (very rough, but conservative) I mentioned in my original response. Then see what you got, and come back for more questions. Good luck.