The shear springs can be used to represent the shear capacity of the soil. The shear springs' characteristic values are defined separately in the direction of the local member axes x, y, and z, and are to be considered as design values.
The individual shear springs can be calculated as follows.
C2,x = axial stiffness (strain stiffness E ⋅ A)
C2,y = resulting restraint around z-axis
C2,z = resulting restraint around y-axis
Shear springs C2,y and C2,z represent constant rotational springs over the member length and are calculated as the product of Poisson's ratio of the soil and C1,z. They are given by the unit [kNm/rad] per [m]. With rad = m/m, this results in the unit [kN].
