stand alone module - fixed support at intermediate span

[genieyas]

Hello,

When calculating a continuous beam at stand alone module of robobat, I can't change intermediate support to fixed type.

Could someone explain this? 

[Artur.Kosakowski]

Hi @genieyas 

I'm not sure if I understand the situation correctly. For the intermediate supports as in your beam you will have negative bending due to the fact that it is a multi-span beam. If you want to have fully fixed supports there then what you got are four separate single span beams instead and you should define them like that in Robot.

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[genieyas]

Hello, 

Rhink you for the the answer;

If Robobat gives me the hand to change the intermediate support to fixed one, it will be very helpful to calculate multi-span beam fixed at all his supports, instead of calculating 4 fixed beams;  However, i don't think the results of the tow methods are the same.

Why "Rrobobat" doesn’t make this possible for users?

Sincerly

i don't think if

[Artur.Kosakowski]

Hi @genieyas 

IMHO there is nothing like a multi-span beam with fixed supports:

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[genieyas]

Hello,

You are right, the same bending moment in the tow cases: Four separated beams fixed and one muli - span beam fixed at all his support.

you also show me the case of multi-span beam pinned at intermediate supports, and you show me the bending moment could you please help me the make the conclusion between : multi span beam pinned at intermediate support and multi-span beam fixed at all support.

Could you ask Robobat to make this option available at next versions, because it is easy to calculate reinforcement with stand alone module. 

[Artur.Kosakowski]

Hi @genieyas 

Let me put this in this way. I'd say if you have a multi-span beam the intermediate supports should be pinned. If you treat the supports as fully fixed then it is no longer a multi-span beam as the load applied on one span doesn't influence the results on the others so in fact you have a number of (separate) single span beams instead.

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[genieyas]

Hello,

very intersting, if i had understand your answer, i can say: With fixed support we have no more multi spane beam, because evcey spane support his aone loud; so it is more intersting to work with multi spane beam to spread excessive loud on one span to the other ones.  ITS RIGHT?

But this give me another intersting question: Once using a model (not stand alone module), and i want to calulate a "Multi span beams", i select all of them, then i calculate, my question is: Is robobat consider them as multi span beam, so it should be pinned, wich is not the case because all the nodes at the model are fixed as the user dosn't make "Relachement"; Or it consider them as fixed, so it dosn' mind to select all of them at one time or one by one?

Sincerly

[Artur.Kosakowski]

Hi @genieyas 

very intersting, if i had understand your answer, i can say: With fixed support we have no more multi spane beam, because evcey spane support his aone loud; so it is more intersting to work with multi spane beam to spread excessive loud on one span to the other ones.  ITS RIGHT?

Correct.

But this give me another intersting question: Once using a model (not stand alone module), and i want to calulate a "Multi span beams", i select all of them, then i calculate, my question is: Is robobat consider them as multi span beam,

Correct

so it should be pinned, wich is not the case because all the nodes at the model are fixed as the user dosn't make "Relachement"; Or it consider them as fixed, so it dosn' mind to select all of them at one time or one by one?

The neighboring spans act as elastic rotational restrains for the span between them.  In other words if you think in terms of a single span beam then the supports are neither fully fixed nor fully pinned but elastic (with springs for rotations) instead.

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[genieyas]

Hello,

I hope it will my last question to close this subject once for all.

So i can say : Once using a model instead of stand alone module, and when i select my beams, Robobat calculate theme as multi-span beam (elastic connections) even if the connections are defined at the model as fixed, and even if the symbol it gives me is a fixed support like the picture bellow.

 

[Artur.Kosakowski]

Hi @genieyas 

When you import a beam from the model the RC Beam design module uses the bending moment diagram as calculated for the model. In such case the supports' shapes should be treated as positions of walls or columns rather than fixed or pinned as the RC Beam module doesn't run any static analysis of the beam at all.

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[genieyas]

Hello,

So the shape of supports when i import my beams from the model doesn’t have any relation with the mechanical type of the support (Fixed or pinned), just show me the positions of my columns and walls and if the wall or columns stop at the current level or not?

But what is the mechanical type of this supports? 

Sincerly

[Artur.Kosakowski]

Hi @genieyas 

So the shape of supports when i import my beams from the model doesn’t have any relation with the mechanical type of the support (Fixed or pinned), just show me the positions of my columns and walls and if the wall or columns stop at the current level or not?

Correct.

But what is the mechanical type of this supports? 

As defined in a model. If you have a column/wall below (and above) the beam then it is an elastic support. The more rigid these columns/walls are the closer to the fully fixed supports you are. The best way of determine what actually happens is to look at the shape of the beam's deformation.

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[genieyas]

Hello,

I could now make the fellow conclusion:

 - Once using RC beams module, the user define the mechanical type of the supports: Fully Fixed or Fully pinned support because, in this case Robobat doesn’t know the columns and wall and if they stop or not.

 - Once import the beams from the model to RC beams module, the mechanical type of support depend on the rigidity of columns and walls, so it neither fully fixed, neither fully pinned.

 My last question, I hope so:

- What about the rigidity of the beams on the right and of the left of the considered beam, do they impact the type of support?

 Sincerly

[Artur.Kosakowski]

Hi @genieyas 

It is a quick check isn't it? 

 

If I managed to answer your question(s) press the Accept as Solution button please. This will help other users to find solution(s) much faster. Thank you.

[genieyas · Accepted solution]

Hello Artur,

Yes your "quick check 🙂 " shows that, the elasticity of the support depend on both clomns above and below,  also the  beams on the right and the left.

I need now to understand more about elastic support and how the calculation is done, this will bring me to put more question about this subject.

i can approuve your answer and look farther to elastic support.

It is very intersting, Think You very mutch Artur

Sincerly