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RE: Powder Actuated Fasteners

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     << Curt La Count wrote:
     
     I would like to see if there is a body of opinion out there concerning 
     the replacement of welds with powder acuated fasteners in horizontal 
     metal deck diaphragms.  I have seen values published in ICBO reports 
     for diaphragm strength values, but I have not seen any stiffness 
     values.  My specific concern is for stiffness degradation under cyclic 
     loads.  Welds resist shears by a combination of tension, bearing and 
     shears due to the circumferential attachment and the pins only bear 
     against the leading edge of the deck.  Would this cause hole 
     elongation and softening of the diaphragm stiffness.  If anyone has 
     experience with this topic, I would appreciate your input. >>
     
     ---------------------------
     
     1) My recent experience is that every contractor wants to install 
     metal deck with powder actuated fasteners.  It would be hard to 
     require puddle welds in today's market.  Puddle welds are too 
     expensive and the installers have more recent experience with the 
     powder actuated fasteners.
     
     2) Hilti publishes some "Flexibility Factor Comparisons" between 
     puddle welds and their fasteners for different deck gauges(January, 
     1994).  The units are inches/Kip, and I assume that they are static, 
     noncyclic values.  These comparisons are not in the ICBO reports.  The 
     published values for puddle welds and Hilti "ENP" fasteners (for metal 
     decking to steel) are essentially equal for all deck gages.  Hilti 
     "EDN" fasteners (for metal decking to bar joists) are from 100% to 
     200% more flexible than the puddle welds.
     
     3) I feel comfortable with the ENP fasteners.  But I have to review 
     the deck shop drawings very carefully to make sure that they specify a 
     specific acceptable Hilti fastener.
     
     Hope this information / opinion helps.  For more information, contact 
     Hilti.  Brian Stocking, PE is the Southern California Regional Field 
     Engineer (800)879-6000, X-7573.
     
     
     Rick Drake, SE
     Fluor Daniel, Irvine