Must i put gravity

[OS]

1).In EQ Analysis( if I only want to do EQ analysis) the gravity load must be put ???

3).and why we do Gravity Analysis,I see all the examples,they all put load on nodes in gravity analysis,as we all kown the structure under gravity the column node has three types of forces:”M,V,N”.now,we puts only “N” on column,consider no “M” and “V”,so is the results from Gravity Analysis has some realistic useness???

[fmk]

no you don't have to do a gravity load analysis.

the examples do gravity analysis befor a transient because most people would want to perform a gravity load analysis before transient .. we are just showing them how it would be done.

[OS]

But we kown this:(there are two reasons)
1.p-delta effect is connect with grivity,if i don't put gravity, the command
Transf Pdelta work aslo?

2.the axis press ratio(can affect damage format of column) is not same between up column and bottom column,if we don't put gravity,however ,we considered the up and bottom column have same axis force,is not make sense!!!