Resin anchor bolts in bridge decks

[mamebraso]

I normally design resin anchors using ETAG guidance since we are not allowed to specify a particular manufacturer to the contractor.
I am working on a bridge deck and i need to resist some forces from a barrier. I am doing this using resin anchor rebar. I have gone through all the checks provided my ETAG annex C. It passes on everything but it seems to fail in concrete edge shear. My question is since etag is based on just the concrete capacity can i assume failure of the reinforcement in the deck as an added capacity? My dowels are 20mm dia situated 697 from edge of deck(depth 240mm). Any direction, material, comment will be appreciated.

 

[MichSt]

I’m not familiar with ETAG. I usually use Hilti Profis to check my adhesive anchor design. If you are designing for a 10-kip impact load, you should be able to get the anchors to work by themselves. I do not include the deck reinforcement to help resist the impact loads with the anchors in my designs. I typically design (or check in the case of railing replacement only) the deck reinforcement to resist the impact loading on its own. Here’s a detail that you could use to get a little more edge distance on your anchors closest to the deck fascia.

See Section 6, guide 6.29.09A

http://mdotwas1.mdot.state.mi.us/public/design/englishbridgeguides/

There are some other details there for railing replacements that may be helpful.

 

[dik]

There's an advantage to spec'ing a specific product and adding the note or approved equivalent... When I first started engineering it was common to use a generic spec, but, I've gotten almost completely away from this. By spec'ing something, you know what you get and if it's a significant cost issue, the contractor will likely raise the question!

Dik

 

[mamebraso]

Thanks guys. I have profis anchor but it is also based on ETAG annex c. The reason i sometimes shy away from it is because it assumes the shear capacity to be evenly distributed on the anchors and sometimes ignore the fact that only the anchors close to the edge when c<10Hef is actually supposed to be carrying the shearforce and may therefore give you slightly higher edge shear capacity. The edge shear capacity is more dependent on the edge distance, depth of member and total spacing of the group anchors. Etag gives very conservative values and also my company are not allowed to specify a particular anchor but to specify minimum depths and sizes of anchor. The contractor chooses the anchors and is supposed to test a percentage of the anchors to confirm the pullout forces.
Thanks anyway