Cracked condition for reinforced concrete columns

Question:

Hello. I have a question about how midas determines for structural analysis what moment of inertia to use for beams and columns. 

 

Given that either the cracked or uncracked condition might be used, I am unsure what the program defaults to, and how to change from one condition to the other like you can do in other programs. 

 

So in the model attached, is the post tension being resisted by the column's gross moment of inertia or is it considering an effective moment of inertia for the columns?

 

AASHTO refers to this in C 4.7.1.3.


Thank You!



Answer:

Hi,

We have received your query. We will get back to you soon.

Regards,
MIDAS Support


Hello,

The said clause is very specific in saying that such reduction in stiffness is to be done for seismic analysis.

Actually, based on the current setting in the model, the complete stiffness of the columns is being used.  It is uncracked.  If it is required to reduce the section stiffness for any particular case, then the section stiffness scale factor and boundary change assignment features have to be used.  Kindly refer the image below and the attached model.


Kindly let us know if further assistance would be required.

Regards,
Nandeep
Technical Manager, MIDAS
Creation date: 10/17/2018 11:17 PM (dklee@midasit.com)      Updated: 10/18/2018 8:55 AM (dklee@midasit.com)
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