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Re: CONC Slab Uplift

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Tarek-	
I believe the operative provision of the '97 UBC 
(which I assume you are referring to since section 
1912.15.5 does not exist in the '94 code) is 
section 1915.8, "Transfer of Force at Base of 
Column, Wall or Reinforced Pedestal."  This does 
allow connections made with reinforcement and 
"bearing on concrete" , i.e, anchor bolts set into 
the footing.  (See the ACI-318 commentary for a 
little additional explanation).  However, with 
that said, a positive, mechanical connection 
would, IMHO, be the preferable detail.  

The provision you cited (Section 1912.15.5) would 
definitely apply at a splice if the tension tie 
were to extend from column to column of the frame 
(again, IMHO, a preferable detail) without relying 
on developing the slab and the bars in the tie 
member were spliced.  At the hairpin, the bar is 
continuous and able to resist the full tension 
capacity of the bar. 

However, more important than the specific code 
requirements is simply the presence of a load path 
for this force.  When I worked for the Office of 
the State Architect, Structural Safety Section 
about 20 years ago, one of the frequent errors I 
found in checking rigid frame school and hospital 
structures was a complete lack of provision for 
resisting this force. And remember, everything 
submitted to OSA required a licensed structural 
engineer to sign (well, an architect could sign, 
however few did. But, that's another thread). 
OSA's checking standards have traditionally been 
the toughest in the State.  It makes me wonder how 
many buildings have been built with this defect 
that went through some of the smaller jurisdiction 
building departments that provide little, if any, 
structural checking as long as it is stamped.

Bill Cain, SE
Oakland, CA