In ACI 318-14 chapter 17 effective embedment depth (hef)is used in equations to determine concrete breakout strength for a single anchor in tension, and for anchor groups. 17.4.2.3 says Where anchors are less than 1.5 x hef from three or more edges the value of hef is reduced to the larger of Ca,max/1.5 or s/3, where Ca,max is edge distance and s is anchor spacing. These values are to be used in equations 17.4.2.1 thru 17.4.2.5.
Then in 17.4.2.9 where factored tensile force exceeds concrete breakout strength if anchor reinforcement is developed according to chapter 25, reinforcing can be used instead of concrete breakout strength in determining strength in tension. BUT only reinforcing less than 0.5 x hef from anchor bolt can be included as anchor reinforcement.
Do you think the same effective depth (hef) used in eq.17.4.2.1 thru 17.4.2.5 should be used to determine required distance for inclusion as anchor reinforcement?
Figure 17.4.2.9 is meant to illustrate the arrangement. It shows hef as the full depth of the anchor embedment, but also shows the failure surface extending horizontally to 1.5 x hef, which leads me to believe that when edges of a pier or column are less than 1.5 times anchor depth from anchor centerline, in order to use rebar in determining allowable tension it must be within (0.5 x Ca,max/1.5) or (0.5 x s/3).
There have been articles disputing this as too conservative, but I am interested mostly in correctly interpreting the ACI code. Do you agree with my interpretation?
Then in 17.4.2.9 where factored tensile force exceeds concrete breakout strength if anchor reinforcement is developed according to chapter 25, reinforcing can be used instead of concrete breakout strength in determining strength in tension. BUT only reinforcing less than 0.5 x hef from anchor bolt can be included as anchor reinforcement.
Do you think the same effective depth (hef) used in eq.17.4.2.1 thru 17.4.2.5 should be used to determine required distance for inclusion as anchor reinforcement?
Figure 17.4.2.9 is meant to illustrate the arrangement. It shows hef as the full depth of the anchor embedment, but also shows the failure surface extending horizontally to 1.5 x hef, which leads me to believe that when edges of a pier or column are less than 1.5 times anchor depth from anchor centerline, in order to use rebar in determining allowable tension it must be within (0.5 x Ca,max/1.5) or (0.5 x s/3).
There have been articles disputing this as too conservative, but I am interested mostly in correctly interpreting the ACI code. Do you agree with my interpretation?
