Different level of support Base Shear scaling up

[SebasR0310]

Greetings!

I'm working on a building in Etabs that has supports at two different levels (see image).

So my question is, how is the right way to do the scaling of the dynamic shear force? i cant do a reading of the "base reactions" table because not all the supports are at the "base" level, and i cant do a reading of the "joint Reactions" table because i used a RS Analysis and all the results will be positive.

I have thought about selecting the first section of the columns and reading the shear forces (V2 and V3) at the bottom section (station 0) for both cases, the static and dynamic, and sacling up from here.

Is my approach correct? do you have another way to do it?

Thanks.

 

[JoshPlumSE]

Do you have a mode that dominates the behavior of the structure? If you have a mode (or Ritz Vector) with a mass participation for that direction above 50% (but preferably more like 70%) then you can look at the mode shape for that dominant mode and interpret the relative signs of reactions based on that mode.

 

[Agent666]

Look at joint reactions instead?