huangyhg

anchor bolt design using aci 349 appendix b
i was reviewing the aci manual of concrete practice 2004.
the aci 349 appendix b - anchoring to concrete is totally revised from the old method which has been around since 1976.
the old method is the method cited in the aisc design guide #7 and has been used extensively to design anchor bolts and other embedments.
the new design method is about three times as hard to use, and it may yield more conservative results.
i just sent a question to aci to find out if they still endorse the old design method.
if not, what about all those millions (billions?) of anchor bolts designed by the old method.
does anyone have any information about this aci change of recommended design proceedure?
regards to all,
jpj
virtualengineer
check out aci 318-02 app d. that has the new procedure also. it's probably the same as what you are looking at but not having seen the 349 i can't say. if it's the same 318 may provide some additional information or commentary. i found it a bit difficult at first but once you understand the procedure it isn't that bad, and it's well suited for a spreadsheet.
i do agree that the aci 318-02 app d is the same procedure as described in the new 349 app b.
my main problem is the old method of multiplying the projected effective area by 4 phi sqrt f prime c to determine the pullout cone strength has been around for years.
was there a failure somewhere to cause this change, and reduction of pullout strength?
what about larger size anchor bolts that are more than 2 inches in diameter or embedded deeper than 25"?
what about all the anchor bolts i've designed using the old aci 349 app b? this was the previously aci endorsed method to design anchor bolts.
i am sure i am not the only engineer who has issues with this sudden change in design procedure.
reviewing some of the other posts in this forum i came upon the referenced article -- alternatives to aci 318-02 appendix d - 鈥淎nchoring to concrete鈥?by colleen bush, p.e. and ed schwieter, p.e. structure magazine 鈥?july 2004"
this article is available free online at structure magazines website
following is the response and question i asked aci regarding using the old aci 349 proceedure to determine anchor bolt pullout.
as you all can see, the old method is still an acceptable design method.
dear mr. **********:
aci publishes codes, specifications, and reports for the concrete user. this message is in response to your technical question/inquiry.
yes, the anchor bolt design method in aci 349 is per the 'old' design method and aci 318 has the concrete capacity design (ccd) approach.
the old design method per aci 349 is still an acceptable design method. the ccd design method has the advantages of easier use, especially with multiple anchor design, and the method more accurately predicts anchor bolt failure for a greater range of anchor bolt types and applications.

a paper on this topic, concrete capacity design (ccd) approach for fastening to concrete, may be downloaded for free for
i am reviewing the provisions of aci 349 appendix b - anchoring to concrete.
i am a little confused because the aci 349.2r-97 (reapproved 2002) embedment design examples appear to use the old design method rather than the newer ccp design method.
does this mean the old aci 349 appendix b design method that we have been using since 1978 and is cited in aisc literature (steel design guide #7), is still recommended by the aci?
or does the aci no longer recommend using the old aci 349 method?
if aci no longer recommends using the old design method i certainly hope there is a good reason to change because there are millions of anchor bolts out there designed using the old design recommendations.
regards,
**********, p.e.

regards to all,
jpj

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