min embedment length for anchor rods?

[hippo11]

Can anyone point me to a reference? Assuming strength works of course. I have heard 12*d as a rule, but haven't found any documentation...thanks

 

[SteveGregory]

Is this for shear or tension? Is this for concrete or masonry?

 

[Lion06]

There used to be minimums in the AISC design guide for base plates, but they went away in the second edition of that design guide. I don't believe there are minimum requirements anymore, just what you need to develop the required strengths per ACI 318 appendix D.

 

[hippo11]

concrete...why does it matter if it's in shear or tension? just worried about cover right now

 

[PEinVA]

hippo11,
Tension splices/embedment lengths tend to be larger than a shear load.

RC
All that is necessary for the triumph of evil is that good men do nothing.
Edmund Burke

 

[hippo11]

just to clarify...i am looking simply for a min embed length rule. strength is a separate issue that i've taken care of...i was just wondering if there's some min out there, perhaps for serviceability, for cover, etc, but it sounds like there used to be a min that was removed from the base plate design guide.

 

[WillisV]

There is really no set minimum. AISC previously had a table with minimums (see Table 8-26 of 2nd Edition LRFD Manual) which ranged from 12db to 17db prior to the "Appendix D" craze. Personally I generally use 12" min. for typical gravity columns.

 

[edwin17th17]

The 12d minimum is found either in
PIP standard
or Design of Anchor bolt design for petrochemical facilities..

 

[Hanif08]

I agree with other posts that there is no minimum embedded length for anchor bolts in tension.

Strength and embedded lengths are related because the strenth is the smaller of tensile strength of bolts or pull-out resistance.

However for shear there is recommended 10d or 12d spacing requirements either from concrete edge or between bolts because of the conical failure mode. If the bolt is too close to edge then it will spall off in shear or if the bolts are too close to each other then there is overlapping of critical regions.

 

[dik]

For shear and tension, I just sum the forces and design as it were tension... in keeping with resistance by shear friction.

Dik