Putting joints at the ends of a beam-column element

[hresquivelo]

How can I put joints within a structure?

Sorry, I didn't know where to place this thread, so I place it in both Documentation and here (OpenSees.exe Users).

Thanks in advance.

[silvia]

this is the right place.
what kind of joints?

[hresquivelo]

Hi Silvia. Those jointed connections that you can encounter on an ideal truss.

Thanks.

[silvia]

1. just use a truss.
2. place two nodes at the same location and connect the other dofs via the equalDof command.

[hresquivelo]

Hi Silvia. Let me see if I understood. For this structure:

The code would be this:

Code: Select all

(...)

model BasicBuilder -ndm 2 -ndf 3

(...)

node 1    0.  0.
node 2    16. 0.
node 3    0.  15.
node 31   0.  15.
node 4    8.  15.
node 5    16. 15.
node 51   16. 15.

equalDOF 3 31  1 2 3
equalDOF 5 51  1 2 3

fix 1  1 1 0
fix 2  1 1 0

(...)

element elasticBeamColumn 1 1 3 $ACol $Ec $IzCol $transfTag
element elasticBeamColumn 2 2 5 $ACol $Ec $IzCol $transfTag
element truss 3 31 4 $ABeam $matTagBeam
element truss 4 4 51 $ABeam $matTagBeam

(...)

Am I right? Thanks in advance.

[silvia]

depends on what you are trying to model.... trusses???

[hresquivelo]

No, any structure that has those jointed connections in its interior, like node 4.

[silvia]

but now you have jointed connections at the other nodes.
why not use beam elements?

[hresquivelo]

Could you, please, tell me how is the code for that structure? Because I don't know how to write it.

Many thanks.

[silvia]

please work through the examples manual, make the necessary changes based on the command-language manual.

[hresquivelo]

Hi Silvia. I read the command language manual and didn't find any specific command in which I could model the node 4 easily. Is there any?

Many thanks again.

[silvia]

no, of course not. but think about your model and what you are trying to model.
it is hard for me to help you, you have to work through it with a colleague.

[hresquivelo]

Don't worry, I'll try to find a solution to this. At the moment, I'm thinking to take advantage of its symmetry. I hope someday OpenSees could handle these kind of joints within a structure.

Anyway, thank you for your continued support .

[zvidrih]

Hi,

if you want to release the bending moment at node 4, just use the following code

Code: Select all

(...)

model BasicBuilder -ndm 2 -ndf 3

(...)

node 1    0.  0.
node 2    16. 0.
node 3    0.  15.
node 4    8.  15.
node 41    8.  15.
node 5    16. 15.

equalDOF 4 41  1 2

fix 1  1 1 0
fix 2  1 1 0

(...)

element elasticBeamColumn 1 1 3 $ACol $Ec $IzCol $transfTag
element elasticBeamColumn 2 2 5 $ACol $Ec $IzCol $transfTag
element elasticBeamColumn 3 3 4 $ABeam $Ec $IzBeam $transfTag
element elasticBeamColumn 4 41 5 $ABeam $Ec $IzBeam $transfTag

(...)

Silvia was suggesting the two alternatives, not the combination of both methods

[hresquivelo]

Hi Zlatko Vidrih.

Then my code is ok, right?

Many thanks in advance.