Ductile Failure Requirement in Anchor Bolts
Ductile Failure Requirement in Anchor Bolts
(OP)
I have a situation where the metal building supplier has specified the number and size of anchor bolts required and the frame base plates have been built accordingly. The problem I am having is that I can not get the anchor bolt design to be controlled by a ductile failure of the bolts since the quantity and the size are larger than required for the loads. Normally I would just try to lap the bolt with the vertical bars in the pier and hook the top to develop them properly. Unfortunatly the size requirements of the pier are not going to allow me to easily fit all the hooks and the anchor bolts in the top of the pier. Also the pier is too shallow to extend the anchor bolt any further to get the extra lap length.
Does anyone have any suggestions on how to get this problem solved?
Thanks,
Does anyone have any suggestions on how to get this problem solved?
Thanks,






RE: Ductile Failure Requirement in Anchor Bolts
Dik
RE: Ductile Failure Requirement in Anchor Bolts
RE: Ductile Failure Requirement in Anchor Bolts
If the pier is that small and that shallow, it seems it wouldn't take much steel before you were developing the entire weight of the footing. Or am I missing something?
RE: Ductile Failure Requirement in Anchor Bolts
I am performing the analysis per ACI-318 App. D and the pier is only 18" tall. If I understand JStephen’s question correctly I can not develop the weight of the footing because I am not extending my anchor bolts down into the footing. I was trying to avoid it because they will be pouring the pedestals separately. I suppose I could if I have no other choice.
I did have a chance to do a search of the IBC ’06 code and I think I found the provision WillisV was referring to. It is in 1908.1.16 and states that ductility can be ignored if the anchors have been designed for more than 2.5 times the load being applied. I'm nearly at three so it looks like this will be my out in this situation.
Thanks again to all!
RE: Ductile Failure Requirement in Anchor Bolts
RE: Ductile Failure Requirement in Anchor Bolts
RE: Ductile Failure Requirement in Anchor Bolts
RE: Ductile Failure Requirement in Anchor Bolts
If you have a pier with "enough" reinforcement, you do not need to worry about the breakout strength calculation. So I would say for many pier anchorage situations, the rebar in the pier will satisy RD.4.2.1 and you would just calculate steel in tension and pullout in tension and call it a day.