Often the designer is trying to debond the bolts so that the anchorage behaves as assumed in design: tension delivered at the nut/washer/head/plate rather than in a distributed fashion along the bolt. Another reason to debond is facilitate a "stretch length" where the bolt will be prestressed.
Use of a debonding agent is questionable in my opinion. If I really want an anchor bolt debonded, I'll wrap it with something more convincing.
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.
Same as KootK's opinion on bond breaker. If I coat a bar in form release agent and leave it sticking out of a pour I still can't pull it out of the piece. I've probably eliminated much of the surface bond but I still have the mechanical action of the deformations plus the fact that the bar is not perfectly straight and will grab some of the concrete as I try to pull it out. In the anchor bolts case it would be whatever threads are left exposed above the nut.
That said, bond breaker probably does concentrate the force somewhat in the base of the bolt, so may be close enough. Though, if you're going to do something you might as well do it right.
Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
If you need the bolt debonded to plastically elongate in an earthquake or something, bond breaker won't get the job done. If you're trying to match your mathematical model it's just silly, since testing used in developing anchor models don't use a debonding agent.
The only time I have used debonded anchor bolts is to prestress the anchors (like in wind turbine base anchorages), with "high-chair"-type bases of moment-resisting columns, or on prestressed equipment base anchorages. In every case, I specify either a wrapping, or a plastic sleeve, to ensure there truly is no bond there along the rod length. I personally wouldn't depend on a bond-breaker coating only.
Dave
pipe insulation - good for debonding and allowing moderate lateral deflections. However, it is a typical note to "grease" the one end of a smooth rod between construction joints on a SOG. I always figured a column shoe would be a better way to get more anchor length for stretching with the added benefit of a stiffer connection zone.
