×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

rigid connections steel frame

rigid connections steel frame

rigid connections steel frame

(OP)
Hi! I have a problem with abaqus.
I need to create a steel frame with rigid connections between the beam ends and the columns.
I create 3D wire part for the beams and columns, and I assigned the material, profile and section. After I assembly it, and I create the steel frame. How can I realize the rigid connections between the elements?

Thx in advance

RE: rigid connections steel frame

You can use tie constraints or merge parts to realize this type of connection.

RE: rigid connections steel frame

A screenshot, drawing or sketch would help to understand your question.

RE: rigid connections steel frame

If you connect the wire geometrically, then you get common nodes during meshing and the rods are connected to each other.

Otherwise you can use a Tie-constraint or add connector elements between two nodes and use the connector type 'Beam', which is a rigid connector.

RE: rigid connections steel frame

Tie constraints are the best option in such case. Just apply them to all rigid joints (select the two ends of wires connected at a given joint). You may have to change position tolerance if default one turns out to be insufficient.

Hinged connections can be realized using equation constraints.

RE: rigid connections steel frame

(OP)
Thx for your response.
I connect it geometrically and I create a reference point for every floors. In this point I create a Kinematic coupling constraint and I assigned the intertia mass.
But when I try to do the Jobs to evaluate the frequency Abaqus give me this error: Too many iterations needed to solve the eigenvalue problem.
I also try to evaluate only the first shape mode.

RE: rigid connections steel frame

Kinematic coupling is not a good option in such case (I assume that you want the mass to be applied to the whole beam, not just a single node). Check this thread with the discussion about the application of remote mass in modal analysis:

https://www.eng-tips.com/viewthread.cfm?qid=460924

RE: rigid connections steel frame

(OP)
I solve the problem, but the foundamental period is 8.47*10^-22.
There is another strange thing, in the deformed beam, a beam moves, like it's coming off the frame. I don't understand why!!!!

RE: rigid connections steel frame

Did you use tie constraints ? If yes then you should increase the position tolerance. Modal analysis is the best way to visualize disconnected regions and as you say, they occur at frequencies close to zero.

RE: rigid connections steel frame

(OP)
No i connect beam and columns geometrically. I try to use tie constraints.

RE: rigid connections steel frame

If you want them to be connected geometrically you have to make a single part from them. It can be easily done in the Assembly module (using Merge/Cut Instances tool that I've mentioned before). Mesh nodes can be merged this way too.

RE: rigid connections steel frame

(OP)
Sorry but I don't understand.
I do Merge/Cut in Instance tool. I select Merge (Mesh), in options Suppress and in Merge nodes boundary only.
When I do the analysis there is another error: In model....have not assigned a beam orientation, ecc...
But when I create the beam I assigned the beam orientation...

RE: rigid connections steel frame

(OP)
I'll write down the steps I took
1) I create wire part for every type of beam/column
2) I create steel material
3) I create I profile for every type of beam/column
4) I create sections for every type of beam/column
5) I assign section and orientation at every beam/column
6) I assembly the parts with Independend (mesh on istance) and i create my frame
7) I create the step for the modal analysis
8) I create boundary conditions (Encastre) at the foundation
9) I create kinematic coupling constraint every floor with a special join in the centre of gravity. I assign to it the inertia
10) I create the mesh

RE: rigid connections steel frame

Merge/Cut Instances tool creates a new part and instance so you may have to reassign orientations. You can check if they are assigned or not using Query tool in the Property module.

RE: rigid connections steel frame

(OP)
I have combined the various elements, but I have another problem.
The periods grow with the number of mode and they are very big.
what could be the problem?

RE: rigid connections steel frame

Take a close look at the mode shapes (deformations). Do they look correct ? Aren't some parts of the frame disconnected and moving on their own ? Make sure that all units are correct (dimensions, material properties and point mass/inertia values).

RE: rigid connections steel frame

(OP)
All the parts of the frame are connected, i check it. I think that a possible problem is the units, but i don't understand why the periods growing!?!?

RE: rigid connections steel frame

Do you mean that each of the subsequent modes has higher eigenfrequency ? This is normal, natural frequency extraction procedure finds either selected number of subsequent modes or all modes in a given range of frequencies. Then it displays them in order from lowest to highest frequency.

RE: rigid connections steel frame

(OP)
Yes i solved the problem. thx!!!!

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

eBook - Integrating the Engineering Ecosystem
Aras Innovator provides multiple options for integrating data between systems, depending on the scenario. Utilizing the right approach to meet specific business requirements is vital. These needs range from authoring tools, federating data from various and dissimilar databases, and triggering processes and workflows. Download Now
White Paper - Industry 4.0 and the Future of Engineering Education
With industries becoming more automated, more tech-driven and more complex, engineers need to keep their skills and knowledge up to date in order to stay on top of this wave—and to be prepared for the Industry 4.0 future. The University of Cincinnati offers two online Master of Engineering degree programs designed specifically for practicing engineers. Download Now
eBook - The Design Gridlock Manifesto
In this eBook, you’ll learn 6 ways old CAD technology slows your company down and hear how design teams have put those problems to rest. “The Design Gridlock Manifesto” shares first-hand modern CAD experiences from 15 companies around the world. Download Now
White Paper - Comparing Multi-Patterning at 5nm: SADP, SAQP, and SALELE
Self-aligned multi-patterning techniques such as SADP, SAQP, and SALELE are increasingly popular at advanced nodes, but each process has its pros and cons. IMEC and Mentor, a Siemens business collaborated to identify potentially less-obvious process and design limitations and trade-offs between the three SAMP techniques. Learn more in this paper. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close