Anchor Bolts 1

[jcrickey]

I have designed a 65 ton bearing press and now must attach it to a foundation. As a mechanical my knowledge of concrete is limited. I have searched some literature an have some formulas, but I do not know if these are the best for my situation. The load is in the horizontal direction this causes a tension force about 25ksi in one of my anchor bolts (FEA model). The formula I used for a j-bolt suggested 27.77" for a factor of safety of 3 with 3000psi concrete. I dont have this kind of depth available. Any suggestions on formulas or anchor types other than j-bolts? I would like to keep the foundation to 24" is this reasonable?

 

[jike]

J- bolts and L-bolts are not recommended anymore since the hook portion tries to staighten out under load. I would suggest an anchor bolt with a straight embedment. The embedded end should have some threads so that a heavy hex nut can be installed. For short anchor bolts or those with a sleeve, you should consider adding a plate on the embedded end.

Per an article "Design of Headed Anchor Bolts" in the Engineering Journal of AISC, 2nd quarter 1983, the embedded portion shall be:

Fu (ksi) min. embedment
58 12d
90 - 120 17d
150 19d

This values may have to be increased depending upon the edge distance and the spacing of the anchors. These values are based upon ACI 349.

Both references are useful.

 

[UcfSE]

Please note that this thread is cross-posted in the "Foundation Engineering" forum and has received replies there also.

thread256-140434

In the future try to restrict posting to one forum unless you have received no replies after a reasonable amount of time.

 

[RHB51]

I would suggest to contact either Hilti or Simpson Strong-Tie for their anchor bolts. They have a multitude of different anchors with easy to use design charts.
Be sure and watch your spacing and edge distance's.
Randy

 

[JStephen]

Get ACI-318, current version, one of the appendices has what you need on the anchor bolt design.

 

[jimzpe]

Foundation thickness limitation for a 65 ton press? May consider rethinking this system. I don't recall having this problem when designing large equipment support bases. You also should include sleaves with these anchors for proper pretensioning and positioning (again requiring "extra" thickness).

 

[jjf1]

I agree with jimzpe - the press manufacturer may need mass dampening of their equipment, this is typically provided in the foundation. also agree with the sleeve, I've had a lot of success with DECO anchors.

One suggestion: have you considered isolation type anchors?

jjf

 

[jcrickey]

___ ____
/ / / /
/ / / /
/ /PPP PPP/ /
/ / / /
/ / / /
-----------------------------
/ /
/ /
-----------------------------
X X X X X X
X X
X X

This is a crude drawing of the press. The "P" is where the pressing happens in the horizontal about 31" above the
box beam, which is 196" long. This causes the beam to deflect up. The anchors "x" are shown,the 3X locations are the anchors with the high tensile stress. The reason for the limitation on the thickness is due to existing electrical and gas lines. The electrical lines can be moved, however the gas pipeline is not ours it just runs under our facility. I could put a beam across the top but this interfers with overhead crane operations. Thanks for the information,I will check with local anchor dealers.

 

[jimzpe]

You've got way more potential problems then just anchor lengths based on that last post. Hire a professional.

 

[jcrickey]

The gas and electric lines are not a problem. We have had them checked out and know the about the clearance issue. That’s the reason for keeping the depth of the footing to a minimum. This is just a research phase. When and if the plan is implemented the design will be authorized by a professional. We do realize the potential problem that exist, that’s the reason for the questions. As mechanicals we stick to designing rail cars, however when a new idea for improved manufacturing arises as a company we look at the idea before hiring a professional.

 

[jimzpe]

Didn't intend on being critical and thanks for the explain. Been in that environment before and know your situation and the procedures. Your correct in researching about all you can on the install prior to bringing in the Professional. Sure makes our job easier working with people like yourself.

With limited thickness the most prevelent issues will probably be having a foundation system with enuf mass to prevent long term problems from vibration (press is not a compressor or similar object but the problem still exist). The type of bearing strata has big influence on this also. A majority of the time, if I can make a smaller (thinner) foundation than I like work, a solution can be found for your anchorage problem and still be economical. I've anchored big equipment with creative systems before (did similar thing with a bar-b-que grill mfgs. press). Don't sweat the bolt, make sure the system as a whole stays put first when that 65 ton press goes "BANG".

 

[dicksewerrat]

Unless the gas main is a high pressure, over 80psi, have it moved. The Gas utlity won't want your machine on top of it. Makes for tough maint. Then the foundation and bolts can be designed properly. Gas Co. may move it for free.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com