Base plate design - using support reaction or beam end force

Hi, everyone.

I encountered a doubt while I am designing Base plate of Steel column.

The question is which output should I use for my base plate of Steel column.

Which one is normally recommended when designing Piperacks or Equipment supporting steel structures ?

- Situation1) Using Beam end force of the steel column with modeling of concrete pedestal or

- Situation2) Using Support reaction of the steel column without modeling of concrete pedestal.

Situation 1)

- Structural steel frame and concrete pedestals are modeled.

- Support conditions are given to the bottom node of concrete pedestal

- Bottom node of steel column has beam end release condition according to the structural configuration and anchor bolt arrangement

- Then, I get beam end forces of the steel columns and can use them for designing of base plates.

- And, additionally, support reactions are used for designing concrete foundations

Situation 1)

- Only Structural steel frame are modeled. (concrete pedestals are not.)

- Support conditions are given to the bottom node of Steel columns according to the structural configuration and anchor bolt arrangement

- Then, I get support reaction at the bottom side of the steel columns and can use them for designing of base plates.

- And, in this time, duplicated and modified model with concrete pedestal is required to get output for concrete pedestal and foundation design.

I am waiting for your opinion.

Thank you!

YJ Kim