I have Modelled a Modular building in Opensees. This Includes Boxes( Modulesmade 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 Pdelta 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 Pdelta 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 Pdelta effects? is there any other way to account for that? Or is it not the Pdelta 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.
PDelta Effects for Models With Elements which doesn't include Geometric Transformation
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Re: PDelta Effects for Models With Elements which doesn't include Geometric Transformation
For this case, leaning column is the only option to consider pdelta 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 ?
Re: PDelta Effects for Models With Elements which doesn't include Geometric Transformation
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?
"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?