×
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

What appropriate load combination for tank leak test

What appropriate load combination for tank leak test

What appropriate load combination for tank leak test

(OP)
Hi guys, i was designing a wastewater RC tank on ground. I am taking 1.4(D+F) for operation case, F as fluid load. My design basis calls for American Codes (ASCE. ACI350) and such operation load case is clearly defined. But i could not find in the codes on how to deal with leak test load combinations. Am i going to take such fluid as live load 1.2D + 1.6 Water Test? Some of my colleagues are suggesting to take alternative load comb 1.4D + 1.7Test, which i felt is too much for the situation. I'll be thankful for any help to enlighten me.

RE: What appropriate load combination for tank leak test

Since I design a lot of repairs on wastewater treatment tanks, by all means use the 1.4F and try to optimize the test case. We can always use the business.
Or you can do what we do and use 2.21 times the fluid loads for bending and 1.7 for shear to whatever you have as a passive overflow, like the tops of walls.

RE: What appropriate load combination for tank leak test

(OP)
Thanks Jed. But could you guide me where how to get 2.21 for bending? is this about durability factor? Sorry im not good with tank design.

Also, as with this Sd, i read from ACI350 that Sd could be ignored when load combination is with seismic. I was thinking maybe the reason was that seismic load is only short term. If my intuition is correct, then i could also ignore Sd for wind and for test load, since they are not long term forces. I may be wrong, would be thankful to be enlightened

RE: What appropriate load combination for tank leak test

First of all, ACI 318 is wrong. Fluid loads, while potentially well defined, should have a much higher load factor than dead loads. ACI 350, some edition, somewhere, says to use a 1.7 factor and add a 1.3 factor to that for "durability" for bending. Shear requires a 1.7 factor, unless you need shear reinforcing, than you use the 2.21.
You're right, SD can be ignored when combined with seismic. But seismic is likely to not control vs. the overflow level on the vessel.
One last piece of advice; these tanks, full of wastewater or water, are not to be trifled with. I can't mentor you, but someone should be watching.

RE: What appropriate load combination for tank leak test

(OP)
Thanks a lot for this guidance Jed

RE: What appropriate load combination for tank leak test

I think I'm following your logic, but please check me: Since these are test cases (not long-term operations), do you ignore seismic added stresses for the four-five hours of the static test for waste tanks? (I'm more familiar with the pipe and ASME type hydro tests, op tests.)

RE: What appropriate load combination for tank leak test

Leak tests last a lot longer than four to five hours, but the principle is basically what you stated. Based on the risk of a seismic event occurring during the leak test, it can be reasonably ignored.

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


Resources

Research Report - How Engineers are Using Remote Access
Remote access enables engineers to work from anywhere provided they have an internet connection. We surveyed our audience of engineers, designers and product managers to learn how they use remote access within their organizations. We wanted to know which industries have adopted remote access, which software they are using, and what features matter most. Download Now
eBook - Managing the Context of Product Complexity Using the Digital Twin
Keeping track of changes to complex products is difficult—think Aerospace & Defense equipment, new generations of commercial aircraft, and software-based automobiles. A new way to managing the digital context of the physical product is required and the answer is the Digital Twin. This ebook explores the opportunity available for Operations and Maintenance for the Digital Twin. Download Now
White Paper - Trends in Industrial Filtration
Substantial progress has been made in filtration technologies in recent years. New filter media materials, designs and processes have led to filters that are more efficient, reliable, compact and longer lasting. This white paper will discuss the various trends that are impacting operational responsibilities of MROs today and the resources that are available for staying up-to-date on the latest filtration solutions. Download Now

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