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

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IsmBaha
Posts: 140
Joined: Sun Nov 17, 2013 11:00 pm
Location: University of Arizona

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

Post by IsmBaha » Wed Jun 24, 2020 7:26 pm

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
Posts: 140
Joined: Sun Nov 17, 2013 11:00 pm
Location: University of Arizona

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

Post by IsmBaha » Tue Jul 07, 2020 5:08 am

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

selimgunay
Posts: 913
Joined: Mon Sep 09, 2013 8:50 pm
Location: University of California, Berkeley

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

Post by selimgunay » Mon Jul 13, 2020 10:15 pm

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
Posts: 140
Joined: Sun Nov 17, 2013 11:00 pm
Location: University of Arizona

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

Post by IsmBaha » Tue Jul 14, 2020 5:55 am

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
Posts: 913
Joined: Mon Sep 09, 2013 8:50 pm
Location: University of California, Berkeley

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

Post by selimgunay » Fri Jul 17, 2020 8:12 pm

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
Posts: 140
Joined: Sun Nov 17, 2013 11:00 pm
Location: University of Arizona

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

Post by IsmBaha » Mon Jul 20, 2020 6:42 am

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
Posts: 913
Joined: Mon Sep 09, 2013 8:50 pm
Location: University of California, Berkeley

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

Post by selimgunay » Mon Jul 20, 2020 12:48 pm

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.

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