topic Re: Modeling complex walls in Robot Structural Analysis Forum

Modeling complex walls

Anonymous — Wed, 16 Jul 2014 05:34:17 GMT

Hello,

I want to model a "sandwich" wall which has two outer layers of thin reinforced concrete and a core layer of masonry. How can be done? the overall thickness of the wall is 6cm rc concrete (layer1)+ 50cm masonry (layer 2) + 6cm rc concrete (layer1), overall thickness 82cm. Should I go for volumetric structure instead of planar finite elements?

Kostas Bourmpakis

Re: Modeling complex walls

Artur.Kosakowski — Wed, 16 Jul 2014 06:52:27 GMT

I can think of 3 options:

1. Use a solid model

2. Use a shell model with 3 panels connected with rigid links

3. Use a shell model with a user defined orthotropic thickness

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Re: Modeling complex walls

Anonymous — Wed, 16 Jul 2014 10:48:32 GMT

Thank you Mr. Kosakowski for your answer.

It is difficult for me to understand the procedure for the following option:

3. Use a shell model with a user defined orthotropic thickness

I dont see any option in the user defined for modelling 3 layers as composite.

Additional help please?

Re: Modeling complex walls

Artur.Kosakowski — Wed, 16 Jul 2014 10:57:58 GMT

Indeed such definition is not available directly but you may try to use this one instead:

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

Re: Modeling complex walls

Anonymous — Wed, 16 Jul 2014 11:32:18 GMT

Sorry (it must be me) but I dont get it.

How I ll find and enter the following values for 3 layers with different material?

· membrane stiffness matrix D

· bending stiffness matrix K

· shear stiffness matrix H

Regarding the second solution of 3 panels connected with rigid links, is it enough with the rigid links on the border lines? does it calculate the material as continuous between the layers/panels? it performs as one element?

Finally what is a solid model. first time I ecounter it

Re: Modeling complex walls

Anonymous — Thu, 17 Jul 2014 06:47:23 GMT

Since i am struggling to cope with this task, could someone be so kind and provide me a brief guidance

or an example (if it exist) regarding the modelling of a 3 layer wall composed from 2 external layers of reinforced concrete

and an internal (core) of masonry. I didn't expect it to be so complicated....

Kostas

Re: Modeling complex walls

Anonymous — Thu, 17 Jul 2014 10:42:03 GMT

Come on.... there should be a champion in this forum to help me!

Re: Modeling complex walls

Artur.Kosakowski — Fri, 18 Jul 2014 06:15:29 GMT

I don't have the exact formulas for the stiffness matrix for such type of sandwich wall. You may try to search the web for something like this:

http://contrails.iit.edu/digitalcollection/1968/AFFDLTR68-150article17.pdf

On the other hand you may also consider the following approach if you find it acceptable:

1. Create a composite profile in the Section Builder of Robot

2. Calculate its weighted properties

3. Define a new thickness with material and thicknness that matches the EA* value for the calculated section

4. Use the IY reduction to match EIz* value of the caclulated section

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.