## semi rigid connection

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varafkhami
Posts: 5
Joined: Tue Jan 29, 2013 6:36 am
Location: Shiraz university

### semi rigid connection

Hello
I need to modeling semi rigid connection in portal steel frames(E.Bayo modeling of semi rigid connection or cruciform element)in opensees to pushover analysis.
Thanks

fmk
Posts: 5866
Joined: Fri Jun 11, 2004 2:33 pm
Location: UC Berkeley
Contact:

### Re: semi rigid connection

well the only way to do it is at duplicate nodes at a joint and a rotational spring to model the semi-rigid connection. you can either constrain the translational dof or have springs here as well. do note that your periods are going to change. i suggest you play with a portal frame and the effect on periods before you go big.

Halim
Posts: 13
Joined: Sun Feb 10, 2013 9:19 pm
Location: Kabul University

### Re: semi rigid connection

Thanks,
that solved my problem same as stated in above

varafkhami
Posts: 5
Joined: Tue Jan 29, 2013 6:36 am
Location: Shiraz university

### Re: semi rigid connection

Hi ;
I have a 12X12 stiffness matrix for each 2d frame connections;how can I add new element with this stiffness matrix to being assembled with other element;
Thank you very much.

fmk
Posts: 5866
Joined: Fri Jun 11, 2004 2:33 pm
Location: UC Berkeley
Contact:

### Re: semi rigid connection

if the dof at the element nodes match the other elements framing into the node you need to do nothing .. if they are different you need to create duplicate nodes and tie the nodes together with the equalDOF command.

varafkhami
Posts: 5
Joined: Tue Jan 29, 2013 6:36 am
Location: Shiraz university

### Re: semi rigid connection

in each connection nodes have 3 dofs match to other element nodes, but stiffness matrix for this element is different from other element.how can apply this matrix ?
thanks.

fmk
Posts: 5866
Joined: Fri Jun 11, 2004 2:33 pm
Location: UC Berkeley
Contact:

### Re: semi rigid connection

how is it different!!!

varafkhami
Posts: 5
Joined: Tue Jan 29, 2013 6:36 am
Location: Shiraz university

### Re: semi rigid connection

In this method we replace beam to column connection by a cruciform element that 4 nodes exist in corner of this element(this element has dimention in X and Y direction).when this connection is semi rigid we have a 12x12 stiffness matrix for this element according to 4 nodes (and 3 dofs in each nodes);now how can apply this matrix to define new element for connections ...
thanks a lot.