Horizontal gravity in pseudo-static analysis

[skamalzare]

Hi,

Is there anyway to turn on/off the horizontal gravitational acceleration (i.e. $b1) in quadUP elements?

element quadUP $eleTag $Node1 $Node2 $Node3 $Node4 $thick $matTag $bulk $fmass $PermX $PermY <$b1=0 $b2=0 $t=0>

I am trying to perform a pseudo static analysis, and I want to first perform the vertical gravity to define the loads, and then add/activate the earthquake horizontal load.

Maybe something similar to updating permeabilities after gravity analysis.

Thanks,
Soheil