Spacing Requirements of Post-Installed Anchors

[BSVBD]

I specify Simpson more than Powers and HILTI.

I use catalogs more than software.

In comparison, HILTI catalogs are just plain difficult to read, in addition to the literally dozens of pages per fastener or adhesive.

Assuming the competing manufacturers are reasonably, competitively similar:

WHY do the adhesives have such a large spacing requirements in comparison to the mechanical fasteners?

One reason is that the larger spacing requirements are for tension applications. I understand that.

For static / non-dynamic applications, when I am restricted to close spacing configurations, I have decided that, the adhesives will actually be better, since, by application, the adhesive will "adhere" the associated concrete, and thus, prevent cracking.

This seems so simple.

Am I missing something?

Please advise...

Thank you!

 

[SLTA]

The engineering folks at Simpson are great and always happy to explain the whys behind their requirements or experiments. Call the main number and ask for the engineering group.

Please remember: we're not all guys!

 

[KootK]

The adhesive anchors have two features that I could see affecting minimum spacing:

1) for the same anchor diameter, the drill hole diameter is larger.

2) they deliver a larger portion of the resistance closer to the surface.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[NorthCivil]

I'll bite...

connection design is complicated. There are endless possibilities for how any bolted connection can come together. that's why the catalogues have dozens of pages per fastener.

if you prefer to use catalogues more than software, learn how to read them. I prefer the software - its great, and cuts down on human error (my own).

there is no one size fits all spacing requirement for any fastener.

As to why close spacing isn't recommended ? well, if you drill your holes too closely, you're just going to blow out your concrete. while epoxy is stronger than concrete locally, it still creates an interruption in the concrete matrix.