Hilti Under Cut Anchors For Underhung Crane

[witer]

A runway was installed for a 5 ton underhung crane. It is suspended from a concrete ceiling with embedded headed anchors. Due to a screw- up a pair of support locations failed to be installed. I work for the crane installer. The customer's engineer has suggested Hilti undercut anchors. I have looked at the Hilti specs and am aware that it is suitable for fatigue applications. I am aware of how these replaced the failed epoxy anchors at the Boston dig.

I am not comfortable in using these anchors for suspended crane loads. I would appreciate to hear about experience with this type of application.

 

[dik]

I'm OK with them... but, if someone is uncomfortable using them for this type of application, use another means of anchorage. I don't do things I'm not comfortable with...

Dik

 

[hokie66]

What else would you do? The Hilti undercut anchors are the most reliable of the drilled in anchorage devices, unless you can through bolt.

 

[witer]

I would prefer through bolt. The consultant is opposing this solution because it would penetrate roofing that has already been installed. A review of the Hilti literature shows these anchors used with cranes. It is however seats supported on wall plates. This loading would be combined shear/ tension with tension probably being the minor component. I wouldn't have a problem with that kind of installation..

 

[hokie66]

I agree that through bolts are the best solution structurally. If you are uncomfortable with anything else, and this is your decision to make, stick with your judgment. You have to sleep at night. Roofing can be repaired.

 

[Tmoose]

No experience with them, but I believe the simplified chain of events that caused/allowed the Big Dig epoxy anchors to fail began with them not being installed correctly (well maybe the "problem" started a few days before that) , and even that would have been OK if they had been tested properly and found to be no good.

100 % inspection and proof testing can reduce a lot of speculation.

 

[dik]

The Big Dig failure was mostly a material one... with quick setting epoxy being inadvertently used. The material used has limited creep resistance.

Immediately after the Big Dig failure, Hilti came out explaining that their products were not involved and that their products were creep resistant.

Dik

 

[paddingtongreen]

Have you presented the question to Hilti? I would think they, if anyone, could set your mind at rest if they answer affirmatively.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[chicopee]

I'll go with Hilti material anytime. The success of their products on our federally funded bridge jobs in Ct. is 100%.
Follow Hilti's instructions.

 

[witer]

The anchor was tested by the International Code Council with results presented in ESR 1546 and is referenced by Hilti in their technical documents. The anchors are suitable for dynamic loads from wind and seismic. The governing document by this organization " Acceptance Criteria For Mechanical Anchors In Concrete Elements " ( 2012) states that criteria is unavailable at this time for the performance of these anchors subjected to fatigue or shock loading.