P-Delta Effects for Models With Elements which doesn't include Geometric Transformation

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HajMaf
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Joined: Mon Jan 07, 2019 7:33 pm
Location: The University of Melbourne

P-Delta Effects for Models With Elements which doesn't include Geometric Transformation

Post by HajMaf » Thu Oct 24, 2019 4:20 pm

I have Modelled a Modular building in Opensees. This Includes Boxes( Modules-made of shell elements) connected with two node link elements to form a building as shown below.

We also developed an experimental model of the same and noticed the results for the top displacement.
I could notice that there is a shift (shifting upward) of the baseline in the experimental results which i believe is due to the P-delta effects while the experimental results, top displacement base line was on Y=0 line, i.e X axis. Also i can see that my Opensees Model has no way of getting P-delta effects activated because Neither two node link element nor the shell elements used to model the boxes have coordinate transformation feature.

May i please get your idea on this? how can i let my Opensees model take in to account the P-delta effects? is there any other way to account for that? Or is it not the P-delta effects that's causing the shift of the base line?

I tried adding a leaner column, but it wasn't successful. i followed the exact procedure mentioned for that on Opensees website. But the eigenvalues were imaginary.

selimgunay
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Location: University of California, Berkeley

Re: P-Delta Effects for Models With Elements which doesn't include Geometric Transformation

Post by selimgunay » Sat Nov 09, 2019 11:49 am

For this case, leaning column is the only option to consider p-delta effects. Imaginary eigenvalue can be because the leaning column itself is unstable as it has a hinge at the bottom and connected to only axial trusses. Did you assign masses to the leaning column ?

HajMaf
Posts: 4
Joined: Mon Jan 07, 2019 7:33 pm
Location: The University of Melbourne

Re: P-Delta Effects for Models With Elements which doesn't include Geometric Transformation

Post by HajMaf » Sun Nov 10, 2019 1:51 pm

Hi Yes, i assigned masses to the leaning column. But still i keep getting imaginary Eigenvalues. IS the leaning column method valid for 3D models as well? mine is a 3d Model, but i assigned a leaning column to the first frame of the building only.

"Imaginary eigenvalue can be because the leaning column itself is unstable as it has a hinge at the bottom and connected to only axial trusses" if this is the case, what do you recommend to solve this issue?

Doostihaa
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Re: P-Delta Effects for Models With Elements which doesn't include Geometric Transformation

Post by Doostihaa » Tue Nov 12, 2019 3:10 pm

IS the leaning column method valid for 3D models as well? mine is a 3d Model, but i assigned a leaning column to the first frame of the building only.
https://www.doostihaa.com/1398/08/22/دا ... انگشت.html
https://www.doostihaa.com/1398/08/22/دا ... -پوست.html
the leaning column itself is unstable as it has a hinge at the bottom and connected to only axial trusses" if this is the case, what do you recommend to solve this issue?

Doostihaa
Posts: 6
Joined: Tue Nov 12, 2019 12:34 pm
Location: IRAN
Contact:

Re: P-Delta Effects for Models With Elements which doesn't include Geometric Transformation

Post by Doostihaa » Sat Nov 16, 2019 5:15 am

S the leaning column method valid for 3D models as well? mine is a 3d Model, but i assigned a leaning column to the first frame of the building only.
https://www.doostihaa.com/1398/08/25/دا ... و-نیم.html
https://www.doostihaa.com/1398/08/25/دا ... -پدری.html
the leaning column itself is unstable as it has a hinge at the bottom and connected to only axial trusses" if this is the case.


Doostihaa
Posts: 6
Joined: Tue Nov 12, 2019 12:34 pm
Location: IRAN
Contact:

Re: P-Delta Effects for Models With Elements which doesn't include Geometric Transformation

Post by Doostihaa » Sun Nov 24, 2019 5:12 pm


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