PDelta analysis for Pushover analysis ERROR

[venkateshyadav]

Hi,
I am performing pushover analysis for 2D RC frame.
1)Iam using for transformation command for defining elements as " geomTransf ColTransfType PDelta". Is it necessary to define the rest <-jntOffset $dXi $dYi $dXj $dYj> always?
2)When am using PDelta, am getting initial displacement values as negative values. Is it correct? If correct, how to make a graph with positive values by taking those negative displacement values and corresponding Base Shear values in the final plot?
Am showing an example of initial part of the results below:
Disp Base Shear
0.0062 0.0000
0.0130 0.0000
0.0144 0.0000
-0.0019 0.0000
-0.0534 0.0000
-0.1554 0.0000
-0.3134 0.0000
-0.4966 0.0000
-0.7037 0.0000
-1.1284 0.0000
-0.8284 1.3089
-0.5284 2.6195
-0.2284 3.9186
0.0716 5.2092
0.3716 6.4849

so here, the displacement value -0.2284 can I make it to zero, can I add the corresponding base shear value 3.9186 to the other base shear values and take it as final?
3) Is it necessary to do " geomTransf ColTransfType PDelta" for pushover analysis, or is it sufficient to do Linear ?

Thanks in advance