×
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

Precast Concrete Table-Top Machine Foundation

Precast Concrete Table-Top Machine Foundation

Precast Concrete Table-Top Machine Foundation

(OP)
I would like to ask if anyone has experience utilizing pre-cast concrete for a table-top structure supporting vibrating machine / compressor.
My concern has to do with the joints (Beam to Column, and Top Slab to Beams).
The joints will consist of grouted rebar sleeves. The grout is high strength, 14,000 psi (structure concrete strength is 6,000 psi).
The grouted sleeves will develop far in excess the strength of the rebar.
However, since these joints do not consist of contiguous concrete, I'm concerned there could be some unexpected modes of vibration.
Furthermore, the joints will have shear keys and a 2 in. gap between columns and beams which will be filled with the high strength grout.
I am still trying to find data to substantiate that the grout in the joint will not fail due to the vibrations (several million cycles per day albeit at
low stress levels).

If you have had experience with precast concrete structure(s) supporting vibrating equipment or if you have
any comments on the topic, your feedback would be appreciated.

RE: Precast Concrete Table-Top Machine Foundation

As someone who has done a lot of vibrating equipment bases, my gut instincts are saying "no". (Without seeing more detail.) But if you have to go with it.....I'd get specific vendor info on the sleeves. (I.e. do they have any testing results of high cyclic loading?) If they don't have such info, I'm not sure I'd try it. Checking in ACI 215 (their fatigue code) I see no mention of this.

There probably is some data out there on high cycle loads with sleeves in some journal.....but you don't know if your vendor's sleeve will be like that sleeve. (Maybe compare the two?)

That being said, what kind of unbalanced forces are we talking here from this compressor? It's one thing if we are talking a couple hundred pounds.....and obviously something else if we are talking 100-300 kips.

RE: Precast Concrete Table-Top Machine Foundation

(OP)
WARose, thanks for the response. I don't have actual machine data yet.
Centrifugal - 3,000 rpm, 40,000 HP Motor. Possibly 30~40 kips.

RE: Precast Concrete Table-Top Machine Foundation

Yeah, with those kinds of loads.....you are going to need hard fatigue data. You may want to search for a vendor that does a lot of AASHTO work. Sometimes people use (types of) precast in bridge work.

EDIT: As a alternative, you may want to change connection type(s). If you made it out of A36 steel.....and anchored with headed bolts......that is predictable (and data is readily available).

You may find something on sleeves......but just wanted to suggest this.

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 - PLM and ERP: Their Respective Roles in Modern Manufacturing
Leading manufacturers are aligning their people, processes, and tools from initial product ideation through to field service. They do so by providing access to product and enterprise data in the context of each person’s domain expertise. However, it can be complicated and costly to unite engineering with the factory and supply chain. 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