Load Dispersion

[normm]

I am having a discussion with some friends as to what is the correct method of dispersing a point or line load effects on to structural slab member. The opinions expressed are as follows :

1. You can distribute the load at 45 degrees through floor finish only to the top surface of the slab.
2. You can distribute it at further 45 degrees to the centroid ie midpoint of the slab.
3. You can distribute it still further at 45 degrees to the bottom reinforcement level of slab.

Your opinions and any references you may give will be much appreciated.

 

[msquared48]

It depends what your designing.

If you are designing structural slab steel, then the top of the slab is appropriate.

If you are checking beam or punching shear in the slab, then the bottom is appropriate.

If you are checking the load to the substrata for a slab-on-grade, then the bottom is appropriate.

Mike McCann
MMC Engineering
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