Modeling using member stiffness

[HoshangMustafa]

Hi,

I want to model a 2D concrete structure using the columns' and beams' flexural and torsional stiffness (for example 4EI/L for bending). How should I define them?

[HoshangMustafa]

Hi,

48 views, no replies.

I posted this so I could compare ARSA results with those of hand calculations.

[HoshangMustafa]

Hi,

Isn't it possible?

[Rafacascudo]

I really did not understand the problem. L is given by you model . E can be created by you with the value you want on job preferences/materials.

And both Is can also be set on "new section" dialog , general tab.

[HoshangMustafa]

Hi @Rafacascudo 

I wish I could model a 3D structure (slabs, beams, columns) using 2D frame (beams and columns beneath) by Equivalent Frame Method recommended by ACI code. I tried with elastic release, but without success.

[HoshangMustafa]

Hi @Rafacascudo,

Should I give up this thread?

[Rafacascudo]

I do not know how to do it as I do not work with ACI.

Probably you should seek official autodesk help

[HoshangMustafa]

Hi @Krzysztof_Wasik,

Any help would be highly appreciated.

[HoshangMustafa]

Hi @Krzysztof_Wasik,

I'm afraid it can't be done.

However, another question:

How one can change bar diameter in Required reinforcement module?

[Krzysztof_Wasik]

Hi @HoshangMustafa 

Regarding bar diameters for required reinforcement

For RC slabs it can be done from Reinforcement tab in Slab/Shell Reinforcement type

For RC members beams/columns on Longitudinal reinforcement and Transverala reinforcement tabs from Calculation parameters definition

If it is necessary it is possible to modify available diameters in selected database from Job Preferences >Datababses >Reinforcing bars

Modified database should be saved then Robot should be restarted to see new/modified bars.

[HoshangMustafa]

Hi @Krzysztof_Wasik 

Thanks for your reply. What about my first inquiry in this post? If you're familiar with ACI code, it recommends, among others, using Equivalent Frame Method for two-way slab analysis. So that a 3D structure can be analyzed as a 2D frame using flexural and torsional stiffness of members. How the stiffness can be input into Robot? Is it convenient to use elastic releases?

[Krzysztof_Wasik]

Hi @HoshangMustafa 

You can define arbitrary flexural (Iy)  and torsional (Ix) bar member stifness using Ax, Iy, Iz tab in section definition dialog. Then you can use this section to simulate your 2D frame (or rather grillage structure).

Elastic releases (defined from Elastic tab in Releases dialog) can be also used for arbitrary bar  in Robot.

Yoy can define them as arbitrary Elastic coefficient (RX -torsion, RY - flexural in your 2D simulation) or in respect to beam stiffness (partial stiffness coefficient)