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RE: Garage Floor in Residential House

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The problem is probably the use of a 2x member as a nailer on top of the steel. The typical detail requires a 3x member because the length of the nails (8d or 10d) for the diaphragm and the hangers is longer than 1-1/2" and thus won't penetrate the steel.
I have had to use a 2x nailer in order not to exceed the floor depth when considering the depth of the steel and nailer. 
To solve the problem, I specified Simpson N10 nails for the connections. The N10's are only 1-1/2" long and therefore seat very well. You might try this as a solution to get the plywood flush to the nailer.
 
Dennis S. Wish PE
 
-----Original Message-----
From: Rob Quiring [mailto:robq(--nospam--at)uniserve.com]
Sent: Friday, February 05, 1999 12:12 PM
To: seaint(--nospam--at)seaint.org
Subject: Garage Floor in Residential House

I have a garage floor that is 21'x21' square, that supports cars and light trucks (50 psf live load + 60 psf dead load) and is constructed with 2x12 DFir @ 12" o.c. (span 10') flush framed into a steel W14x30 steel (simple support) beam that spans 21' from front to back at the middle of the garage.
 
a 2x4 is bolted on top of the bottom flange at 36" o.c. each side of the beam. the 2x12 are framed on top of the 2x4 with blocking every second space.
 
2x4 strapping run perpendicular at 16" o.c. on top of the 2x12 to allow for venting, with 5/8" plywood, waterproof membrane, and 4" of concrete on top.
 
my problem is that there is a 1/2" gap between the top of the steel top flange and the plywood floor above providing no lateral support for the beam at the top flange.
 
my Question is: do the 2x12's framed tight against the web of the beam, which stop 1/2" shy of the bottom of the top flange provide lateral support for the top flange of the beam when the beam is in compression?
____________________________________________________
Rob Quiring
Isaak Engineering
Abbotsford, BC