drill-in wedge anchor design for vibrating tension loads 1

[slipstick50]

For vibrating tension loads on drill-in anchors (redhead or kwikbolt) what type of safety factor should be used...

r.

 

[kvillebasser]

Not to avoid your situation, but in tension connections subject to vibration, I try to stay away from wedge anchors of any type. I think you'd be better served to use expoxy anchors.

I have found in the past, even in structures that are not subject to vibration, that wedge type anchors tend to loosen over time. I do not know why they do that, other than to say the grout or concrete that they are placed into, in my cases, typically is less than 60 days old......and I wonder if curing shrinkage has something to do with it.....or it may be that the contractors do not follow the installation guidelines for these anchors (cleaning out the opening well, correct hole diameter, etc).

I would advise you to ask Hilti, Rawl, or whatever manufacturer you plan to use, what their research shows for anchor capacity subject to vibration. I would think they'd point you to epoxy anchors as opposed to wedge type anchors.

 

[slipstick50]

We strongly advise not to use drill in wedge type anchors.. Correctly designed drill in and epoxy set anchors, we have had good luck with.. The problems we have been seeing are structure failures due to wedge anchor loosening and failing. We notice the manufacturers manuals often indicate a 4 to 1 safety factor on anchor load ratings.. Some manuals, in the very fine print say that a 10 to 1 safety factor might be needed if vibration occurs, but contact the manufacturer... contractors and owners go ahead and just use the standard anchors (4 to 1) and failures result......

r.

 

[pmkPE]

The manufacturer of the connection/fastener will specify whether or not the particular bolt is acceptable (i.e. tested) for dynamic loading. If the manufacturer does not qualify it for dynamic loading you direct all liability towards yourself/firm for any failures of the product and the structure/equipment that the connection is used with.