Mechanical expansion anchors in post-tension construction 1

[stookeyfpe]

I have a 7 story Group S-2 (parking garage), Group B (business office and amenities center) and Group R-2 (student housing) building under construction. I'm reviewing the shop drawing and calculations submittals. This is podium style construction where the 1st-3rd floors are IBC Type IA construction and floors 4-7 are 2015 IBC Type IIIA construction.

The fire protection contractor has noted that slabs are PT (post tension). The FP contractor has not provided the data sheet for the expansion anchors. For this and 23 other reasons the plans are not approved.

Frankly I kind of embarrassed to ask this question because PT construction is commonly employed in my jurisdiction and I know that 2015 IBC Table 1705.3 requires special inspections. However, I can see a scenario where the Structural Engineer of Record (EOR) may prohibit their installation. So the question is have any of you fine designers encountered this situation and do you RFI the Structural EOR? I'm of the belief I need documentation that the Structural EOR needs to allow the use of these type of anchors. We have no seismic design requirements in my jurisdiction.

I do know these anchors would be subject to Special Inspection. As to if this is happening is up to the Building Inspector.

As always I appreciate your candid analysis and opinions. Thank you for your time.

 

[TravisMack]

Are you talking about something like the Hilti HDI-P? If so, then no, we have not done anything special for structural review of these anchors in PT slabs.

Typically, most of my customers do inserts, like the Blu-Banger or similar. The HDI-P are just used if something changes and the insert location no longer works.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, LLC

http://www.mfpdesign.com

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[stookeyfpe]

Travis,

The contractor didn't specify the type of anchor. My experience is that most of FP contractors use the Hilti HDI-P inserts in my jurisdiction.

Also, thanks for the response.

 

[TravisMack]

One thing I see many contractors miss: If they are not doing inserts, then they are limited to 10' hanger spacing on 4" and larger when using post-installed concrete anchors. I'm sure you know, but just a heads up in case.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

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[bmlxd40]

The Hilti HDI-P are the most commonly used concrete anchors here in Atlanta. 99% of the hangers here are installed using the HDI-P. Pre-installed embedded type anchors are extremely rare around here for sprinkler contractors, though many of the other MEP trades use them. And yes, Travis, you are correct, most of us have missed the requirement you mentioned above. The HDI-P anchors don't go deep enough to cause an issue with PT cables.



I am actually going to be starting a project soon where it will be the first time I have used embedded anchors as a designer. We will be setting them using a Total Station to locate the anchors in the slab prior to the pour, or something along those lines.

 

[SprinklerDesigner2]

For the ones I have done I submit the anchors and where they would go to the structural engineer of record for his written approval because it is his call.