How to define offset cross section along the length of an element?

[IsmBaha]

Hi!
I have a quick question. Is there a way to define a section or element that is offset from the center line of the adjacent element? For example, if a 15 foot column with a block-out consists of 20x40 cross section for 10 feet, 20x20 for 3 feet but flushed on the face of the 20x40 section, and 20x40 for 2 feet, how can we provide that offset 20x20 section? How do we do that using fiber based elements and/or elastic line elements?
Thanks,
Baha

[IsmBaha]

Anybody knows how to do this? Selim Hocam, do you know?

[selimgunay]

You can only do it with a fiber section by defining the section geometry. The fiber section will automatically consider the asymmetry in the section.

[IsmBaha]

Selim Hocam,

You mean I should shift the centroid of the fiber section and it should shift the element centroid? Just like this below?

set shiftYDir [expr 20.0]; # inches
set coverY [expr $HSec/2.0 - $shiftYDir];
set coverZ [expr $BSec/2.0];
patch quadr $IDconcU $nfZ $nfY -$coverY $coverZ -$coverY -$coverZ $coverY -$coverZ $coverY $coverZ;

[selimgunay]

I think you do not need to shift the centroid of the cross-section. You can consider it similar to defining a T-section

[IsmBaha]

Selim Hocam,
I think I am describing my problem wrong. I am trying define column elements that have different cross sectional dimensions and not aligned at the centroid of each cross section.

Please see this example sketch I created in this dropbox link:
https://www.dropbox.com/s/l75jdbop9lvjr ... s.pdf?dl=0

How can define those elements like the way they are aligned on one face of the columns and at their centroids?

[selimgunay]

Hi Ismail, I see, then one approach can be to define the elements with nodes that correspond to their centroids and connect the ends of the columns (i,e. top end of one column and the bottom end of the other column) with rigid horizontal elements.