QuadUP and 9_4quadUP Permeability coefficient

[mirkomorosi]

Dear all,
I'm implementing site response analysis simulations.
Either quadUP or 9_4quadUP soil elements have been implemented for modeling 1-D analysis.
My question regards Opensees plane-strain elements permeability input parameters ($hPerm=kx and $vPerm=ky).
Permeability coefficients kx and ky for finite elements have [m/s] unit of measures?
My doubt arises since in few web examples (i.e., http://opensees.berkeley.edu/OpenSees/m ... l/4244.htm) I have seen that required input values for this parameter (i.e. given the hydaulic conductivity =0.0003) would be = 0.0003/9.81/1.0 (where 1.0 stands for the fluid mass density).

This doubt would be confirmed from the undertaken comparison between SUMDES and OPENSEES analogous analysis. Output results comparison, given k=5*10-5m/s in the SUMDES input, seem to confirm perm/g/fluid_density expression for OPENSEES since I would get much better pore pressure build-up envelope overlap between the two numerical analysis in case 5*10-5/9.81/1 input values would have been chosen for the OPENSEES quadUP finite elements.

Regards
M.