Anchoring to Existing Concrete

[Champion2022]

I had a general design question regarding anchorage design for a Precast Barrier (30" height) on top of an existing concrete wall and the Precast Barrier is to resist AASHTO TL-2 Loading. Tried initially to use the post installed Hilti Adhesive Anchors but none of their post installed anchors worked unless the spacing is reduced to 5" on center (due to the concrete pull out failure of the post installed anchors). However, i am now considering an alternative using 1 vertical adhesive anchor (#6 at 12" spacing)anchoring 9" embedment into the existing wall and then supplementing it with 2 horizontal anchors (threaded rods) one into the existing wall and the other into the precast barrier connected through a C8 x 18.7 (as in the attached sketch). Would you think this connection is viable for this situation. I am considering that the vertical anchor is stressed to 100% tension capacity of the concrete pull out/bond failure and the remaining tension resistance required is mainly resisted by the lower horizontal anchor into the existing wall. How to check the flexural capacity of the anchor and wondering to check the tension rupture/yielding of the channel web. Appreciate the input.

 

[bridgebuster]

First, the Management does not like posting the same question twice.

Regarding the barrier. your sketch shows a height of 2'-6". Is that an approved TL-2 barrier in your jurisdiction? Presently,2'-8" or 2'-10" is typically used, depending on the particular DOT. Out of curiosity, what's there now? Your sketch shows a bump out in the front of the wall, which is unusual? FWIW, if you don't need a safety shape you could use the Texas Aesthetic barrier, which is 12" wide and is rated for TL-2.

In looking at your scheme, let's assume the vertical bar takes the tension and shear from the impact force and the channel takes equal compressive force that produces shear in the horizontal rods. However, in my mind, although the channel is doing something it's the vertical bar is what's holding the barrier to the wall. Have you looked into Keligrout? It might give you better capacity than Hilti. Keep in mind 5" spacing is that far from a typical retrofit where we have anchor bars every 7 or 8".