×
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

Jobs

R-Value for moment frames

R-Value for moment frames

R-Value for moment frames

(OP)
I'm not seismically detailing my moment frames. Therefore, my steel is designed for R=3. Does anyone see any reason why I can't design my foundation with a higher R? Maybe 6 or even 8? Changing the welding characteristics around the beam to column connection will not change the loads on to the footings. I can't see why IBC would prohibit this.

RE: R-Value for moment frames

One must stay consistent in the whole structure. Except that to stay consistent is mandated by the code to use different R factors, use the same value.

Models are just like theories to reality, ways of understanding the thing.

The loads may be the same but the code may be thinking in that some details require for the targeted reliability different hypotheses to start with. So in the same manner that different methods of ensuring safety for different structural materials are required, also different methods to analyze different components are.

This may or not apply to the question you are asking, yet if there is definite option in the code I would document myself before going against it on my engineering judgement.

This of course is not the case for things one is entirely sure has the whole picture about. But to have the whole picture of things like the implied reliability of the coders is something that escapes more practicing designers, if only -but not only, heh- by their changing nature and lack of time to analyze their always being renewed content.

RE: R-Value for moment frames

   There was another post in the 'structural other topics' forum that was suggesting the opposite, (using a lower R for foundation design).  I think you should use the same R unless the code says otherwise.
  I see what you are saying that how does the foundation know that the frames are not seismically detailed. But there are a lot of things like this in the building codes that really don't make complete sense but we have to do them anyway.

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!


Resources