Lion06
Structural
- Nov 17, 2006
- 4,238
Here is a very generic question on ACI App. D. I have a very good grasp of this material since I wrote a very detailed spreadsheet for it, but I still question the validity of it. Is the only reason that this is required is because of the high stress concentrations associated with headed anchors? If the anchors were deformed and embedments met development length requirements would App. D even exist?
I'm just thinking about a #6 rebar with a development length of 15" (with no reductions).
Let's say for the attached sketch you have a #6 bar hooked with 15" embedment - you have nothing else to worry about, no breakout checks, no side face blowout checks, no pull-out checks, etc. You also get a capacity of 47.5k of tension (for the two anchors in tension).
Now replace those #6 rebar with 3/4" diameter headed anchors with 15" embedment and design per App. D. Now for the same 2 anchors in tension, you get a capacity of 15.3k and it's controlled by concrete breakout (assuming cracked concrete, but using supplementary steel). That's a HUGE difference!
Is the only reason because of the stress concentrations at the head of the anchor?
I'm just thinking about a #6 rebar with a development length of 15" (with no reductions).
Let's say for the attached sketch you have a #6 bar hooked with 15" embedment - you have nothing else to worry about, no breakout checks, no side face blowout checks, no pull-out checks, etc. You also get a capacity of 47.5k of tension (for the two anchors in tension).
Now replace those #6 rebar with 3/4" diameter headed anchors with 15" embedment and design per App. D. Now for the same 2 anchors in tension, you get a capacity of 15.3k and it's controlled by concrete breakout (assuming cracked concrete, but using supplementary steel). That's a HUGE difference!
Is the only reason because of the stress concentrations at the head of the anchor?
