Coupled shear walls with diagonal reinforcement

[farisuwais]

hi team

i have decided to utilize STKO as FE software to carry out my thesis study titled "Investigation of seismic performance
for ductile coupled shear walls". i have some questions related to modelling the shear walls and coupling beam in between.
before jumping to model the coupled shear walls, i am starting with model verification and validation by matching STKO result with experimental results. so i have chosen two specimens of coupling beams tested by Galano and vignoli as shown in the attached figure.

i need guidance whether to model the specimens as 3D solid element or as a shell element.
also for the diagonal reinforcements and the stirrups around them which approach do you recommend to use for modelling in STKO?

[STKO Team]

If you want to save time you can model it with shells.
Regarding the reinforcements, you can choose to model them as equivalent smeared layers, or physically embed them into the shell (The second option can be more accurate)
Check our webinars on RC shear walls.

Then you can choose which approach to follow based on how large are your models, and based on the level of accuracy you want.
For example, if you just need to simulate the detailed response of a specimen, you can go with embedding rebars as fiber-beam elements inside the shell.
If instead you need to model whole buildings you may want to use the simplified (smeared) apporach

[farisuwais]

Dear team

i have decided to model it as solids but i am facing convergence problems. please support as i have tried repeatedly to change the solver, mesh, elements,..etc. but i am reaching a dead end.

Coupling beam.zip

(6.74 MiB) Downloaded 4 times

[STKO Team]

There are some mistakes in your model. Let's try to fix them one by one.

• You have several floating vertices (for example geometry 125, 126, etc...). They are not attached to anything so they will generate a singular stiffness matrix. Probably they come from your CAD drawing, but if a geometry will not be used in OpenSees, delete it.
• Steel plates are not attached to the concrete volume. Again, it will generate a singularity. Please merge them, or provide an interaction between them and the concrete
• Pay attention to the unit system you are using! From the material I can see you are using N and mm, but the self weight is wrong