Fall Protection Concrete Screw Anchor

[joshsgamb93]

Just looking for some professional engineering judgement. The attachment below is a Concrete Anchor Screw for fall protection purposes; however, I find it hard to believe that it would stay in the concrete under the loading of a fall. My judgement is telling me that if it was installed into overhead concrete such that the screw is vertical (perpendicular to the plane of the concrete), it would easily slide out. Are there any calculations/resources I can use to mathematically analyze this screw anchor in the event of a fall?

 

[JLNJ]

The manufacturer of the concrete anchor should have technical information you can use. Most everything is online.

Installed properly, concrete screw anchors can have significant pullout strength; however, each application needs to be verified carefully.

 

[joshsgamb93]

JLNJ, thank you. I have requested any test reports from the manufacturer. I do not have much experience with concrete anchors, but from research I've done online and what I've learned, concrete anchors can have a high pull-out force. Are there any specific analyses I can perform to ensure the anchor does not fail/pull-out?

 

[JLNJ]

The manufacturer will have specific installation instructions to ensure that the anchor performs as advertised. If an anchor is installed properly into sound material, it won't "pull out".

Of course, you need to determine the force on said anchor (or anchor group). This involves engineering the anchorage system as a whole, which will provide you with the anchor forces. Once you have the forces, you can proceed with the anchor selection.

 

[Agent666]

It's also pretty usual for these types of anchors to be tested and certified to the loads required by design before they are put into service. This involves testing against the design fall arrest load in situ on the project site.

 

[human909]

"Are there any calculations/resources I can use to mathematically analyze this screw anchor in the event of a fall?"

Shear pull out and cone pull out based on the tensile strength of concrete.

However concrete screws are among the most sensitive to installation imperfections. If your drill bit starts to wander and your hole size ends up 1 or 2mm wider then you can lose significant strength. This is far less of an issue with wedge or glue based anchors.

 

[Lomarandil]

Yes, if in doubt, design the anchorage per engineering principles and the manufacturer's guidance, then test a few with sandbag dummies to check installation quality.

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just call me Lo.

 

[joshsgamb93]

Thank you all for your help/assistance!