×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

ETABS - Moment Frame Beam Type

ETABS - Moment Frame Beam Type

ETABS - Moment Frame Beam Type

(OP)
I am modeling a steel frame considering an intermediate moment frame as the lateral load resisting system.

All the beams are simply supported except the ones in the intermediate moment frame.

In ETABS, when I view the assignment of any of the simple beams, I find that they are assigned a Moment Frame Beam Type of "Standard Moment Connection". I want to remove this assignment as they are not continuous nor do they have fixed supports. How can I do that?

Below is a screenshot of the Assignment window for your reference.

Thank you.

RE: ETABS - Moment Frame Beam Type

These are special types of connections that are typically used for seismic design and where areas of plasticity may be expected. You should leave this as 'standard moment connection' unless it is your intent to change them for special connections. You should select the frame members you want to pin, and go to ASSIGN -> FRAME -> RELEASES/PARTIAL FIXITY and release any of the components that you wish (most likely M2 and M3 at each end). This will create simply-supported behaviour for the beams you assigned it to.

RE: ETABS - Moment Frame Beam Type

(OP)
Thank you fracture_point. This is what I did. However, I do not understand why ETABS forces me to define the connection as a Standard Moment Connection although the beam is pinned from both ends. This has consequences during the design check as ETABS is checking these beams considering the seismic limit states (AISC 341) although these members are not part of the moment-resisting frames I defined for the structure.

RE: ETABS - Moment Frame Beam Type

What seismic checks is it imposing? Can you share a screenshot?

RE: ETABS - Moment Frame Beam Type

(OP)
Thank you. Below are screenshots of one of the infill pinned-pinned beams in the structural frame. Please let me know if you require additional information.





RE: ETABS - Moment Frame Beam Type

I have come across these flags before as well and I have also found it odd that there is not true explicit way to turn these off.

What I typically do when I get those silly seismic flags is change the framing type from IMF to OMF (even though these beams are not part of the lateral system). This will typically remove the odd seismic warnings.

S&T

RE: ETABS - Moment Frame Beam Type

(OP)
Thank you. This removed the seismic warning but I don't know why we need to define the beams as moment frames although they are pinned from both sides. I just want the beams in the Intermediate Moment Frames I defined in the Structure to be part of the moment frames (not all beams).

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



News


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