Minimum embedment length for anchor rods on a concrete pedestal?
Minimum embedment length for anchor rods on a concrete pedestal?
(OP)
Hello people! I'm new at this and I hope I get some help around.
I'm designing the anchor rods on a concrete pedestal for tension and shear usnig the Design Guides for AISC 01. My result is to use 4 anchors of 1-3/4" of diameter and with that configuration I can manage all the minimal distances on my base plate and pedestal. However i've been searching for a minimum embedment length for those anchors and can't find any.
The design gives me 5" of depth of embedment (hef) using the concrete breakout cone.I found on an old AISC (2nd edition) that for A36 steel (i'mm using that) one should make that anchor of at least 12 times the diameter, but that's and old Manual and i would like to know if there's something more new to it.
I couldn't find anything on ACI318 Appendix D, neither ACI349 or AISC-13th edition.
Does anyone know if that minimum of 12d is still on use? Or has it changed? Or maybe there's not even a minimum?
Thanks!
I'm designing the anchor rods on a concrete pedestal for tension and shear usnig the Design Guides for AISC 01. My result is to use 4 anchors of 1-3/4" of diameter and with that configuration I can manage all the minimal distances on my base plate and pedestal. However i've been searching for a minimum embedment length for those anchors and can't find any.
The design gives me 5" of depth of embedment (hef) using the concrete breakout cone.I found on an old AISC (2nd edition) that for A36 steel (i'mm using that) one should make that anchor of at least 12 times the diameter, but that's and old Manual and i would like to know if there's something more new to it.
I couldn't find anything on ACI318 Appendix D, neither ACI349 or AISC-13th edition.
Does anyone know if that minimum of 12d is still on use? Or has it changed? Or maybe there's not even a minimum?
Thanks!






RE: Minimum embedment length for anchor rods on a concrete pedestal?
Please give some information about how much tension and shear load you have. Based on 1.75" dia bolt looks like your tension might be very high. and based on app. D if you are getting hef = 5" But it seems low. what is the size and depth of pedestal?
RE: Minimum embedment length for anchor rods on a concrete pedestal?
Max Tension = 132 kips
Max Shear = 62 kips
Base plate = 15.74" square
Plate thickness = 5/8"
Pedestal square 23.6"
Pedestal Height 40"
Base plate is embeded on pedestal on center.
Actually the tension requires 2 anchors only, however, tension+shear requires 4-1.75" anchors. Based on my the concrete breakout cone, I would only need a small length for the anchor to work, however my boss and I found on old codes about that 12d minimum and we aren't sure about it.
Thanks a lot!
RE: Minimum embedment length for anchor rods on a concrete pedestal?
RE: Minimum embedment length for anchor rods on a concrete pedestal?
I believe you are designing the embedment wrong for pedestal.
1. Develop the anchor and rebar, Ld.
2. Check the pullout strength per ACI appendix D.
3. Check sideface blowout but usually ignored if you meet minimum edge distance.
4. Check Tension and Shear of Anchor Bolt.
Get a copy of Anchor Bolt Design for Petrochemical Facilities.
RE: Minimum embedment length for anchor rods on a concrete pedestal?
RE: Minimum embedment length for anchor rods on a concrete pedestal?
RE: Minimum embedment length for anchor rods on a concrete pedestal?
132 kips anchor bolt tension is big. You'll be crazy to use less than 12d.
RE: Minimum embedment length for anchor rods on a concrete pedestal?
How could you do anything so vicious? It was easy my dear, don't forget I spent two years as a building contractor. - Priscilla Presley & Ricardo Montalban
RE: Minimum embedment length for anchor rods on a concrete pedestal?
2. The standard practice in this case is to extend the anchor rods so the breakout plane crosses fully developed rebar sized to take the tension load.
RE: Minimum embedment length for anchor rods on a concrete pedestal?
RE: Minimum embedment length for anchor rods on a concrete pedestal?
RE: Minimum embedment length for anchor rods on a concrete pedestal?
The 12d embedment was an old recommendation out of AISC's base plate design guide. That recommendation is now gone, but we still use it in our office.
RE: Minimum embedment length for anchor rods on a concrete pedestal?
Your 5" embed result is way way too short, no matter what code you're using.
Better to use ACI318 chapter 12 (lap anchor bolts to vert bars), not App D.
RE: Minimum embedment length for anchor rods on a concrete pedestal?
RE: Minimum embedment length for anchor rods on a concrete pedestal?
Also take a look at this link: h
RE: Minimum embedment length for anchor rods on a concrete pedestal?
RE: Minimum embedment length for anchor rods on a concrete pedestal?
RE: Minimum embedment length for anchor rods on a concrete pedestal?
RE: Minimum embedment length for anchor rods on a concrete pedestal?
As indicated previously, you do not have to "ignore App. D" to take advantage of rebar development. Per ACI 318-08 concrete breakout strength may be replaced by the design strength of reinforcement provided that development length is provided per Ch 12. If one ignores App. d completely, some failure mode other than concrete breakout may control the design and not be accounted for.
RE: Minimum embedment length for anchor rods on a concrete pedestal?
It provides anchor bolt design example with the option of using Anchor Reinforcement to replace concrete Tension and Shear breakout strength as per ACI 318-08 Appendix D clause D.5.2.9 and D.6.2.9