Displacements and deformations

[Nairi85]

Good afternoon!
I am interested in one question. Please tell me how the robot determines the values of the strains in the concrete elements (columns, beams, slabs) on the stage of the calculation? When not selected class of concrete and reinforcement options, and made the calculation reinforcement design?

This question does not arise for example for steel structures, as in the determination of the structure at the stage of the modeling, it contains all the necessary data for identification of of deformations values.

Thank U!

[Rafal.Gaweda]

These are elastic calculations so in short strain = stress / Young modulus
or I did not understood your question.

[Nairi85]

Rafal.Gaweda thanks for the answer!
If I understand correctly, the Robot in the primary calculation for determining the values of the deformation takes as its basis the Young's modulus of concrete? Can you share an example of calculating the formulas?
And the second question: if the calculation of the reinforcement slab has already been made, how to come back into the model and see the changing values of deformations after a specific embodiment of reinforcement?

__________________________

Rafal.Gaweda спасибо за ответ!

Если я правильно понял, Робот в первичном расчете, для определения величин деформаций берет за основу модуль Юнга бетона?  Можете поделиться примером расчета по формулам?

И второй вопрос : если расчет армировании плиты уже сделан, как правильно вернутся в модель и посмотреть изменении величин деформаций после конкретного варианта армирования ?      

[Rafal.Gaweda]

If I understand correctly, the Robot in the primary calculation for determining the values of the deformation takes as its basis the Young's modulus of concrete? Can you share an example of calculating the formulas?

???????

What kind of formulas? strain = stress / E ?

FEM theory ?

Here : http://forums.autodesk.com/t5/robot-structural-analysis/autodesk-robot-verification-and-theory/m-p/3...

And the second question: if the calculation of the reinforcement slab has already been made, how to come back into the model and see the changing values of deformations after a specific embodiment of reinforcement?

Not possible to update whole model.

On stage of slab provided reinforcement you can calculate slab deflection with real rebars using Verification + With Stiffness Update (FEM)...

[Nairi85]

''Not possible to update whole model.

On stage of slab provided reinforcement you can calculate slab deflection with real rebars using Verification + With Stiffness Update (FEM)...''

Good evening! Many thanks for the answer, in many respects the language barrier prevents me to understand your answer. If possible, please indicate the answer to my second question in the screenshots.

[Nairi85]

I am having difficulty in the program.
I expect a simple console monolithic slab. Please see the model, and explained to me why the Robot gives so different results ??

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[Nairi85]

Friends, please see my files ...

[Artur.Kosakowski]

I expect a simple console monolithic slab. Please see the model, and explained to me why the Robot gives so different results ??

I'm not sure if I understand you correctly. What results do you actually compare and what you consider as being not as you expected? Required vs. provided reinforcement?  Elastic vs. cracked deflection?

If the latter see: http://forums.autodesk.com/t5/robot-structural-analysis/long-term-deflection-problem/td-p/5509553

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.

[Nairi85]

Artur, the same console plate with identical loads and properties calculated by the rules SNiP 2.03.01-84 and EN 1992-1-1-2004.
Results differ by almost 4-fold.
Please see the model:  http://joxi.ru/GrqMj0dsxXGYrz

http://joxi.ru/MAj0E87Fo0k7me 

http://joxi.ru/82QVBGpSpL95Ad

[Artur.Kosakowski]

Hi Nairi,

I'm sorry but I'm not able to make the comparison of results for two different codes and tell that one is wrong and the other is right. I remember making such test for shear reinforcement in a beam according to old Polish code (which was based on SNIP in this area) and then newly introduced EC2 with two sets of concrete struts inclinations. The results (areas of shear reinforcement) for each scenario were entirely different (by far less reinforcement for PN/SNIP) but perfectly right according to the selected code. 

On the other hand if you indicate what for particular check is done correctly and why you think it is wrong then we will try to investigate this area. Thank you for your understanding.

[Nairi85]

Artur thanks for the reply.
But for me it was a problem that occurs seriously, in terms of confidence! There can not be such a difference in the results! If the difference was small, I would have considered it as the difference between the codes. But as I said the difference is very large, and as a builder I know from practice that is not correct. It can not be that one code calculation gave reinforcement bar diameter F14 and F25 on the other code.
Artur I do not ask to compare the results, please see both the file and my screenshots, and please specify the reason for such different results. It is very important to me, I'm always inclined to trust RSA, but such moments are always there are big doubts.

[Artur.Kosakowski]

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.

[Nairi85]

Good afternoon!

Artur I work in the 2014th version of RSА, and there is no function that you have shown.
Or do you want to say that before the 2015th version Robot is not properly consider the reinforcement shell for this code ??

I very much hope that all the same it is not so ...

[Artur.Kosakowski]

In older versions it was assumed that stress value is reduced to the level for which the linear behavior of creep can be assumed. In v.2015 the available range of reinforcement calculations settings was expanded to allow for nonlinear creep which is as you can see a choice rather than "replacement". This is a part of the continuous process of adding new and improving existing features of the program. 

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.

[Nairi85]

Arthur thanks for the answer! I am very pleased that the SAR always evolving and improving.
But still please tell me how to solve it older versions of the problem?
After the building and also to the 2015th version is calculated and constructed.
My specific task is very simple, it can be and the old-fashioned piece of paper to calculate, so I want you to know at what point calculation went wrong and why the robot gave no such tangible results.

[Artur.Kosakowski]

I'm not sure if I understand you correctly. What kind of the solution do you mean? 

You can find the reference to the paragraph of the code in the description of the discussed check box. 

[Nairi85]

I mean, as in the 2014th version of RSA to obtain a correct reinforcement for this slab for EN 1992-1-1-2004.

[Artur.Kosakowski · Accepted solution]

As in Robot 2014 this option is not available the results you obtain are the same as when you switch off use of this option in Robot 2015. To be able to use this option you need to use version 2015 instead of 2014.

[Nairi85]

Artur wanted to ask you one question, I hope the answer to it, not as a support specialist robot, and as free from the company Autodesk, engineer.
If you had to calculate the reinforced concrete building into a robot, and you would not be a difference on what code to work, and would like to achieve maximum real-Results, what rules would you put in your program ?

[Artur.Kosakowski]

If there is no requirement for the design code to use for a project I would use the one that I know best (feel most comfortable with).