Rc column design according to russian code. Frozen reinforcement.

[Anonymous]

Hello, support!

Design of rc column. I have some problems:

1) I freezed my reinforcement to get M-N curve for existing reinforcement in the column, and now I want to unfreeze it. How to do it? When i run calculation i switch off freezing, but it doesn't help.

2) with freezed reinforcement i got the curve M-N for a column. According to this curve maximum axial force(without bending), which can be taken by this column is about 3700kN. Section geometry of the column is 600x300mm(concrete B30), 12 reinforcement bars of d25, A400. I made simple calculation axial(compression) capacity for this column and i get:

Nrd= 0,6x0,3x17x0,85(strength for compression of concrete) + 59x400/1,15(strength for compression of steel) = 2601 + 2052= 4653kN. So axial according to RSA looks much less. 

Note: slenderness of columns(stability check) according to russian codes taken into account by increasing the bending moment.

I attached my file. Please, can you give quicker answer for question nr.1 and of course it would be great to get any comment for question nr.2.

[Anonymous]

After some additional trials I can make my conclusion:

RSA not able to design rc column according to russian code. Program doesn't recognize the grade of steel. 

Waiting for answer from support.

[Romanich]

You  must use reinforcement database according to SNiP 2.03.01-84 with steel A-III etc.

[Anonymous]

Any answers for question number 1?

Romanich, reinforcement database SNiP 2.03.01-84 doesn't change anything. When i define the same layout of reinforcement with the same number of bars, but with different steel grade(for example with A-I and A-III), I get the same curve.

[Rafal.Gaweda]

Any answers for question number 1?

Quick test movie : http://screencast.com/t/fjG0YIMfGwm

[Anonymous]

Thanks! Question nr.1 is solved. I didn't see this button in the top.

What about the question number 2?

[Rafal.Gaweda]

Have you considered eccentricities in your hand calcs?

[Anonymous]

Rafal, did you read my first message?

[Rafal.Gaweda]

Basing on table 15 it seems your settings are gammab2=0.9, gammab3=0.85

So you should set in Robot:

And you will get:

[Anonymous]

Rafal, can you send me your file please.

[Rafal.Gaweda]

Here you are.

[Anonymous]

Rafal, are you joking???

why you switched off the coefficient 0,85?? why you ad high humidity?

my hand calcs in message nr.1 taked into account coefficient 0,85. I only forgot the coefficient 0,9.

So, modified axial capacity without bending for concrete B30, section 60x30cm, reinforcement 12d25A400 must be:

Nrd= 0,6x0,3x17x0,85x0,9(strength for compression of concrete) + 59x400/1,15(strength for compression of steel) = 2340 + 2052= 4392kN

If you want to switch off the coefficient 0,85(concreting in layers <1,5m), hand calcs will be different - without 0,86 coeff. The results would be:

Nrd= 0,6x0,3x17x0,9(strength for compression of concrete) + 59x400/1,15(strength for compression of steel) = 2340 + 2754= 5094kN>>>>>>4350kN(in yout file)

[Anonymous]

Support! Can you explain, what is this???? See attached pictures. One picture from vrification manual(russian)! Is it possible to design column according to SniP 52-01-2003? How? Please, explain me as soon as possible.

[Anonymous]

and one more thing. Can you upload the M-N curve from this verification example(with reinforcement layout)

[Rafal.Gaweda]

New Snip code is available only for required reinforcement calculations.
Sorry for typo error in code name in verification example

[Anonymous]

Rafal,

1. SniP 52-01-2003 is not a new code. New Russian code for concrete is SP 63.13330.2012.

2. So, according to which code verification done in verification file?

3. If it is done according to old code SNiP 2.03.01-84, so how in this example(example 4 in verifiication manual(Russian codes) for SP 52-101-2003, page 11) could be defined reinforcing steel A400? In post 3 of this topic, Romanich said that I MUST to use reinforcement A-III(or A-II, A-I) in calculations according to this code.

4. I asked to upload the curve M-N from this example. Didn't get any answers.Is it possible? Or is it confidence? May be it would be better to get original file of this example.

5. I need this file as soon as possible, beacause I need to do calcs for columns for REAL project, but i still not sure that Robot do it correctly. You can't provide me answers for my questions, so it would be enough for me to get this file only to understand if RSA suitable software for design of concrete columns according to russian code.

Thank you!

[Rafal.Gaweda]

Use new Russian code for concrete SP 63.13330.2012 or the old one SNiP 2.03.01-84.
We do not have these verification examples.

[Anonymous]

you have verification document and you don't have verification file? Mysticism! Can you provide information who did this verification(for column)? Hope Autodesk knows who did this tests 

[Rafal.Gaweda]

 Hope Autodesk knows who did this tests 

old snip, years ago,  Sistema Certifikacii GOST R Gosstandard Rosii, Moscow....

Going back to subject. It seems you are right. It seems AI steel is always taken for RC column design regardless your settings.