Question:
I have problems understanding how to model elastic surface foundations. Where do I enter my modulus of foundation? And what is the meaning of the other surface support parameters?
Answer:
In RFEM, a surface foundation is described by five parameters:
- On one hand, there are three moduli of subgrade reactions in the directions related to the local surface axes (C-u,x, C-u,y, and C-u,z). C-u,z is technically equal to the Winkler modulus of foundation. It can be obtained from a soil report. This foundation can also be assigned to a nonlinearity, such as failure under tension; see Image 01. The parameters C-u,x and C-u,y describe the resistance of the foundation against horizontal displacement in the respective directions.
- On the other hand, the parameters for considering the shear capacity of the foundation (C-v,xz and C-v,yz) are of importance.
The modulus of subgrade reaction for the bedding of a foundation, for example, must therefore be entered in the C-u,z field, as the bedding acts perpendicular to the surface.