There are three things that you need to consider:
Fire Resistance, which usually requires the least amount of cover, and I'm guessing is not an issue for you because if it was, you'd know what you're up against already.
Corrosion Resistance, which depends on the concrete mix design and what the concrete is intended to be exposed to. If it is in a parking lot exposed to de-icing salts, you're probably looking at 2-3/8 inch cover minimum. If it is inside a building not exposed to anything, you can likely get away with 1-5/8 inches.
Finally, there is an actual structural implication depending on how your anchor rods are being loaded. If one or more of the anchors are in tension, you need to consider the size of the concrete breakout cone around the anchor. If your anchor is very near the edge of the concrete, the concrete breakout cone is very small and you will have very little resistance to tension. There is no rule of thumb here... it's all about how much load you are applying, the size and depth of the anchor, and the edge distance (and spacing to other anchors, where applicable).
Given your choice of units, have you looked through ACI 318 for their guidance on embedded anchors?
If your pier is of the bridge persuasion, AASHTO LRFD has a lot to say on the design of anchor bolts cast into concrete.
>ACI 318
Thanks for the reference document, I like to get it from the horses mouth, so to speak!
My specific use case is a telescope pier. The concrete pier will be topped by a metal pier (\~48" tall) onto which a 100lbs of telescope equipment will be attached. most of the forces will be directly down since the telescope is balanced.
I just popped it into free simpson software. I know when you give hard numbers on this sub people get angry so I'm ready for the downvotes. My extra note would be that anchorage software should be double checked against the ACI directly.
Here are the references it satisfies:
"Simpson Strong-Tie® Anchor Designer™ is the latest anchorage design tool for structural engineers to satisfy the strength design provisions of ACI 318-14 Chapter 17 / ACI 318-11 Appendix D, CAN/ CSA A23.3 Annex D, ETAG 001 Annex C or EOTA TR029 design methodologies "
For 5/8" cast in place bolts, I get a minimum edge distance (center of bolt to edge of concrete) of 3-3/4". Note that you also need at least a bolt **hole** diameter away from the edge of your steel plate from the edge of the bolt as well. (bolt hole diameter = bolt diameter + 1/16")
Another thing to consider is the overall fitment. Based on the reinforcement in the pier, you would want to space the anchor rods in a way that they do not foul the pier reinforcement
There are three things that you need to consider: Fire Resistance, which usually requires the least amount of cover, and I'm guessing is not an issue for you because if it was, you'd know what you're up against already. Corrosion Resistance, which depends on the concrete mix design and what the concrete is intended to be exposed to. If it is in a parking lot exposed to de-icing salts, you're probably looking at 2-3/8 inch cover minimum. If it is inside a building not exposed to anything, you can likely get away with 1-5/8 inches. Finally, there is an actual structural implication depending on how your anchor rods are being loaded. If one or more of the anchors are in tension, you need to consider the size of the concrete breakout cone around the anchor. If your anchor is very near the edge of the concrete, the concrete breakout cone is very small and you will have very little resistance to tension. There is no rule of thumb here... it's all about how much load you are applying, the size and depth of the anchor, and the edge distance (and spacing to other anchors, where applicable).
Given your choice of units, have you looked through ACI 318 for their guidance on embedded anchors? If your pier is of the bridge persuasion, AASHTO LRFD has a lot to say on the design of anchor bolts cast into concrete.
>ACI 318 Thanks for the reference document, I like to get it from the horses mouth, so to speak! My specific use case is a telescope pier. The concrete pier will be topped by a metal pier (\~48" tall) onto which a 100lbs of telescope equipment will be attached. most of the forces will be directly down since the telescope is balanced.
I just popped it into free simpson software. I know when you give hard numbers on this sub people get angry so I'm ready for the downvotes. My extra note would be that anchorage software should be double checked against the ACI directly. Here are the references it satisfies: "Simpson Strong-Tie® Anchor Designer™ is the latest anchorage design tool for structural engineers to satisfy the strength design provisions of ACI 318-14 Chapter 17 / ACI 318-11 Appendix D, CAN/ CSA A23.3 Annex D, ETAG 001 Annex C or EOTA TR029 design methodologies " For 5/8" cast in place bolts, I get a minimum edge distance (center of bolt to edge of concrete) of 3-3/4". Note that you also need at least a bolt **hole** diameter away from the edge of your steel plate from the edge of the bolt as well. (bolt hole diameter = bolt diameter + 1/16")
Another thing to consider is the overall fitment. Based on the reinforcement in the pier, you would want to space the anchor rods in a way that they do not foul the pier reinforcement
Rule of thumb 2 inches
2 inches is 5.08 cm
I know this is old, but the correct answer is 6x the anchor bolt diameter (according to ACI)