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

Steel tank wall - combined stresses - D100

Steel tank wall - combined stresses - D100

(OP)
For a steel water tank standpipe (h=60ft, D = 40ft, high seismic) with mechanical anchorage (J = 3). Code is AWWA D100-11.
Plate tension is in the left right direction (X axis) due to static and seismic hoop stresses.
Plate tension is in the up down direction (Y axis) due to overturning "bending" stresses.

The D100-11 code is silent (or appears so) about combined tension. For any other structure regardless of code, I would combine code-level (ASD) tension using "von Mises" criteria (deviatoric stress), and compare the resulting deviatoric demand with design shear strength = 0.577*Fy / Omega.
It appears like Equation 3-3 is for members, not plates. If I combine tensile stresses, I expect some strong pushback from my fellow engineers and reviewers, since I am not following the code (but instead following mechanics of materials).
This tanks meets the code if combined stresses are not considered.

RE: Steel tank wall - combined stresses - D100

Plate stresses in that case are not normally combined.
To be honest, the vertical tension is not normally even checked, just the compression, and the allowable compression will be a fraction of the allowable tension. The only failures I've ever heard of relating to vertical stresses in a shell were all compressive failures, and that is the limiting factor in the code design.
If I'm visualizing it right, the seismic hoop stresses would be highest on the compression side of the shell, for that matter. The formulas calculate a single stress at a depth, but it's not actually uniform around the tank.
Note that there is never an effort to fully analyze all the stresses at a point. For example, at a circumferential seam where thicknesses differ, you get bending stresses which are not normally calculated or considered in the design. Ditto at the corner weld, where the bottom is presumed to be yield. You get residual stresses in the shell due to rolling, forming, and welding that are not calculated or considered in the design.

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