Sunday, September 18, 2011

Re: rebar vs anchor


Appendix D does not even consider reinforcement as anchors (for example, D.1), leaving the design of such reinforcement to the governance of "other chapters" of the code (D.2.1).

As proven by decades of research and practical use, the concrete-embedded hooked or straight rebars developed per ACI318 Chapter 12 are capable of resisting full "fy"-level forces.  As a side note, Chapter 12 does not mention the cracked concrete or contain geometrical limitations even remotely comparable to those of Appendix D - and the embedded rebars still have a successful record. 

I am long done discussing the rationality of severe constrictions imposed by Appendix D.  On the practical side, however, these constrictions effectively preclude any reasonable anchorage in cases of high (say, 240,000 lbs net) pullout forces.  At the same time, ACI318 appears to intentionally provide a reasonable option of using the properly designed (including, as Harold mentioned, A706) embedded rebars.  

Thank you,

V. Steve Gordin SE
SGE Consulting Structural Engineers

On Sunday, September 18, 2011 at 8:07 AM, Ben Yousefi wrote:

Good morning Steve


I don't see how an embed plate on top of concrete would get you out of App. D. The current exception is for "multiple anchors connected to a single steel plate at the embedded end of the anchors" which doesn't quite jibe with what you're describing (if I am understanding this correctly).


Ben Yousefi, SE

Los Angeles, CA


From: Steve Gordin []
Sent: Saturday, September 17, 2011 9:37 AM
Subject: rebar vs anchor


Good morning,


Anchoring a piece of heavy equipment with high seismic pullout. 


I can use anchors through the baseplate, and use ACI318 Appendix D.  


I can also weld the baseplate to embedded plate with welded-on hooked rebars.  This case does not appear to be governed by Appendix D, and the results (embedment depths etc.) are quite different.


Your thoughts on this subject will be highly appreciated.


V. Steve Gordin SE

SGE Consulting Structural Engineers