×
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

Stress Concentration

Stress Concentration

Stress Concentration

(OP)
Hi All,
I have the following problem - I have an I-beam. This I beam is replaced with e new I beam, same material, but the middle of the beam is beefed up, which is a stress concentration. Any hints, how should I get away with the new design, addressing the fact that I have a higher stress concentration? Main load of the beam is tension/compression.
Thank you all in advance,

RE: Stress Concentration

Can you describe what you mean by "beefed up"?

RE: Stress Concentration

If it's mainly tension/compression, why would you need to beef up the middle?

RE: Stress Concentration

i think he means mid-span ...

the beefed-up section is designed for the higher loads at the mid-span, right?
you also need to check the un-beefed-up section, where the loads are highest

i guess you can look into the stress concentration effect ... i'd've thought your in-service loads would be so low that you were near the endurance limit of your steel. you wouldn't combine stress concentration with static design loads, right?

Quando Omni Flunkus Moritati

RE: Stress Concentration

(OP)
...the beefed up midspan of the beam was because a hole must to be drilled, so I am planning by comparison of Moment of Inertia prove that the beam is OK, but I am not sure how should I get away with the stress concentration!

RE: Stress Concentration

are you looking at statics or fatigue ? if statics, neglect Kt.

are you looking at the Kt due to hole or at the beefing up transition ? at either location it should be easy enough to calc the stress from bending, and to pick a Kt from somewhere.

Quando Omni Flunkus Moritati

RE: Stress Concentration

Where are you drilling the hole?

RE: Stress Concentration

(OP)
the hole is vertically oriented, in the middle of the cross section. Statically should be OK, my concern is from fatigue point of view in both around the beefedup area and around the hole!

RE: Stress Concentration

so you have a hole in the tension flange ... what's the problem analyzing that ? Kt = 3 ??

Quando Omni Flunkus Moritati

RE: Stress Concentration

(OP)
yes, I do agree, kt=3. So I guess my approach would be to find the max stress and from published fatigue life data in cycles(MMPDS)show that it will be OK for certain amount of cycles?
Thank you all for your thoughts!

RE: Stress Concentration

sounds like a plan ... make sure you're using stresses from typical loadcases (not static design cases)

Quando Omni Flunkus Moritati

RE: Stress Concentration

(OP)
I will, I am working on it, thank you rb1957, appreciate your thoughts!

RE: Stress Concentration

btw, Kt = 3 is reasonable for an open hole (like for a system penetration), if you're filling the hole with a fastener Kt should much less (unless it's a load transfer fastener, when it'll be much higher!)

Quando Omni Flunkus Moritati

RE: Stress Concentration

(OP)
No, the hole is a drain hole, so it is considered opened hole.

RE: Stress Concentration

'bout as open as they get!

Quando Omni Flunkus Moritati

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