Basement design boundary conditions

[stabiliser]

Hi all,

I'm contstructing a basement which is 15mx10m and 3m in height. Since i have no 3d fem software i thought i'd model the whole thing as 5 plates. The four walls as three times fixed and one end free (the top). The floor as 4 time fixed.
After this a redistribution of the moments is in place to have the same moments in all corners. I firstly want to assume that the walls and the floor have the same thickness.
As old Cross learns i would like to take the mean value of the two moments (same thickness of floor and wall).
Only thing is : one wall is for instance 15mx3m, the ratio is 5:1 which is not tabulated in my plate tables since plates have a ratio of 2:1.
Any tips?

 

[ishvaaag]

For most foundations that have a single underground level here the walls are analyzed just as cantilevers on the bottom, using commonly even active push, not even at rest. The minimum geometrical ratios for walls are used for everything else and even for the main cantilever rebar if less.

The mat is another thing and you will have to consider any column loads that may be bearing. If not, you can use a table for simply supported plates and then use the cantilever wall moments to reduce somewhat the required rebar, then apply the minimum geometrical ratios.