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!

*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.

Jobs

FEMA 273

FEMA 273

(OP)
Hi all
In fema 273 and ASCE 41, the modelling parameters and acceptance criteria of concrete flexure members are given as rotations.
I do not know what is meant by rotation. is it the rotation of the plastic hinge or the chord rotation of members (Drift/L).


RE: FEMA 273

Can you reference a particular clause in FEMA 273 for us to comment on? In general, I believe that the criteria are curvatures rather than rotations. Curvature, of course, is a measure of the axial strains induced by flexure.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: FEMA 273

Are you talking about this section:


If so it appears to be a deformation-controlled action as the defining acceptance. So if you establish a plastic hinge at a point on a beam, they are requiring the design to result in a smaller hinge rotation than that listed in the referenced table. This, to me, is the relative rotation of the member on either side of the plastic hinge.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: FEMA 273

(OP)
thanks all for your reply
kootk see Table 6-17

RE: FEMA 273

Thanks for the clarification aladdin76.

Quote (aladdin76)

I do not know what is meant by rotation. is it the rotation of the plastic hinge or the chord rotation of members (Drift/L).

You've got two separate items on the table here. In each case, FEMA-273 is attempting to limit curvature, and thus damage, in the members.

1) Curvature for a shear wall plastic hinge, often located at the base of the wall, is indexed to the amount of rotation occurring over the estimated length of the plastic hinge. That's figure 6-2.

2) Curvature for a coupling beam is indexed to the chord rotation estimated in each of the coupled shear walls that serve as the chords for the composite wall, taken at the elevation of the coupling beam. This is figure 6-3.

The key to understanding this, in my opinion, is to realize that curvature is the parameter of interest for members dominated by inelastic flexural behavior. Rotation and chord rotation are just how we get to curvature.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

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


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