Winkler type elemts - line support stiffness 1

[hockley]

Maybe this is a bit of a basic question - but I'd be grateful if you could give me some advice or refer me to an appropriate website...

When modelling a strip foundation in AxisVM (a 3D finite element package) if I use the default line support stiffness Rz of 1E+7kN/m/m the reactions I get are rather "peaky". I would like, if possible, to make the support elements a little bit softer but I am unsure of how they are working.

In the manual it mentions that the line support elements are Winkler type elements. For a given width of strip foundation and a given ground stiffness how should I calculate the parameter Rz?

Rz has dimensions kN/m/m - is this simply the stiffness modulus of the ground (Es in kN/sq. metre) multiplied by the width of the strip foundation or is there, as I suspect, more to it than that?

Also, if you could give me guidance on how one calculates the value of Rz for ground-bearing slabs (given a certain ground stiffness modulus) I would be very grateful.

 

[Deim]

Dear Hockley,

The Winkler modulus can be estimated by the following expression:
K = E*(1/B+1/L+1/h)
where,
K : Winkler modulus [kN/m3]
E : average Young modulus of the soil [kN/m2]
B : width of the strip [m]
L : length of the strip [m]
h : limit depth of the soil [m]
The expression may be used if the soil layers are nearly horizontal.