×
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

Siesmic Loading on ducting/piping

Siesmic Loading on ducting/piping

Siesmic Loading on ducting/piping

(OP)
Hi,

I've been instructed to perform siesmic loading on ducting and pipework which is already built.
i
The existing detail is basically two M12 rods which hang from for above slab supporting the duct. the connection of the M12 rod is basically fixed in to the slab providing a rigid connection using Hilti products.

My question is, providing the lateral force times the lever arm to the support (bending moment) is less than the bending moment capacity in the M12 rods. is this sufficient? Most guids I'm reading appear to show actual siesmic bracing at 45 degrees. Does anyone know the answer and where I can look for it?

G

RE: Siesmic Loading on ducting/piping

Vertical rods are totally inappropriate to resist seismic lateral loads. cross bracing is required.

RE: Siesmic Loading on ducting/piping

You did not say how big the piping was. Obviously M12 bar is too small for very larger pipe, may be OK for small pipe. Threaded bar is not a good details for side loads. Some conservative load factors are recommended.

RE: Siesmic Loading on ducting/piping

Does the ducting actually need to resist the seismic load, or can it, and the hangers, just sway? More a question for your pipe stress guys.

RE: Siesmic Loading on ducting/piping

Many codes and prescribed approaches for this type of work don't allow rods in flexure to resist seismic restraint loading.

RE: Siesmic Loading on ducting/piping

(OP)
Thanks guys, yes I did some more research on this and it appears got hangers are not a good idea. There we end up using diagonal struts to resist the lateral forces.

RE: Siesmic Loading on ducting/piping

As noted above, hanger rods for mechanical are not meant for bending. Diagonal strut bracing with stiffeners on the verticals is quite typical, spacing would depend on the piping size/weight/function.

There are a lot of good resources for mechanical seismic restraint design.
SMACNA has a code guide and industry standard. FEMA has a booklet.
A lot of suppliers also have great resources, such as TOLCO, Gripple, Unistrut, Kinetics, just to name a few. All free literature on their website for download.

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

White Paper - Considerations for choosing a 3D printing technology
The adoption of 3D printing into major companies’ product development life cycles is a testament to the technology’s incredible benefits to consumers, designers, engineers and manufacturers. While traditional production methods have limitations in manufacturability, 3D printing provides unparalleled design freedom due to the additive method of building parts layer by layer. Download Now
White Paper - Are all 3D printed metals the same?
With so many different 3D printing metal systems and processes today, how can you know exactly what you’re getting? Today, there are several different methods for manufacturing 3D printed metal components with their own strengths and limits. 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