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RE: more aci 318

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As I understand, if the concrete fails first….brittle failure which is what I was having until I arrived at the adequate conc. thickness and bolt embedment.


The code does allow a ductile connection to the bolt to fail prior to concrete failure so you could get around it that way. In my case I am dealing with a pre-manufactured cabinet that I am reluctant to monkey with.




From: Daryl Richardson [mailto:h.d.richardson(--nospam--at)]
Sent: Tuesday, August 05, 2008 9:49 AM
To: seaint(--nospam--at)
Subject: Re: more aci 318




        Why does the bolt itself have to fail in ductile failure?  Why can't a plate or similar detail that is connected to the bolt be used to provide the ductile failure?




H. Daryl Richardson

----- Original Message -----

Sent: Tuesday, August 05, 2008 10:09 AM

Subject: more aci 318


This bolt thing is becoming more frustrating.


I have been doing anchor bolt shear/tension calc for a 1000# piece of electrical equipment mounted on a pad with ½” dia. anchor bolts (manufacturers frame provides holes for ½” dia bolts). The pad is 8’ by 8’.


I have found that a 14” deep concrete pad with cast in place bolts embedded 8” is required for ductile failure, my closest edge distance is 18”. I cannot have brittle failure due to seismic category D.


What used to be a 30 minute calc for loading and bolt design has turned into hours of *&^$%#@ and a pad design that is embarrassing to provide the client and contractor.


Aaaargh !!


Mark D. Baker

Baker Engineering