The OpenSees Community

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?

Hi,

Is Adding leaning column to simulate P-dela effects done ony in 2D analysis?

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.

Hi everyone,

How do we model an Aluminium frame in opensees for Nonlinear analysis? My concern is how to choose Material for it. Obviously we don't have a straight forwad code for it. But What Uniaxial Material do you suggest to be used to Model the Aluminium Material?

Even if we use a Multilinear Uniaxial Material and substitute properties of Aluminium for that we are still only able to feed the Tensile and compressive strengths only,it wont take care of the Shear strength or anything else of the material. Could anyone please suggest what should be chosen (Material) in Modelling an Aluminium frame?