14159
Structural
- May 31, 2005
- 175
I have a very light steel rafter to cold-formed roof joist connecton. I was planning to make this connection with 1/2" A325 bolts, but there is a better product for this particular connection. It's a double-ended A449 bolt that I found. Detailing considerations make this a far better connection than typical bolts. It allows one member to remain secured while the second member is bolted down and is dramatically safer and better than what can be had with A325 bolts.
The problem is that the AISC Spec Section A3 states "ASTM A449 bolts are permitted to be used only in connections requiring bolt diameters greater than 1.5"..." I think that this is meant to apply to real steel connections, like beam-to-girder and beam-to-column connections and other heavy connections. My little connection probably doesn't have 5 kips of load on it and will be controlled by a wide margin by bearing strength at the cold-formed member's bolt holes.
The upcoming 2005 AISC Spec has modified wording, but amounts to the same restriction.
Section A4 is entitled "Anchor Rods and Threaded Rods" and permits A449 of any diamter. What is the technical definition of a "threaded rod"? My bolt is a threaded rod with a washer welded in the middle of it. It ends up with two nuts, one top and one bottom, with the washer in between two of the plies. Can I use this provision to get out of the A3 provision? Is there somewhere in the Spec or otherwise that technically defines a "threaded rod" and/or the uses of a "threaded rod"?
Also, my connection is to a cold-formed member. The 2001 Cold-Formed Spec allows threaded rods, but for diameters less than 1/2" ???!!!?? Does this deep-size the idea?
Considering that the bolt shear and uplift doesn't control by about 8x, I feel the need to wade through the dogma somehow and come up with a justification for this better and safer connection.
Any help would be greatly appreciated.
DBD
The problem is that the AISC Spec Section A3 states "ASTM A449 bolts are permitted to be used only in connections requiring bolt diameters greater than 1.5"..." I think that this is meant to apply to real steel connections, like beam-to-girder and beam-to-column connections and other heavy connections. My little connection probably doesn't have 5 kips of load on it and will be controlled by a wide margin by bearing strength at the cold-formed member's bolt holes.
The upcoming 2005 AISC Spec has modified wording, but amounts to the same restriction.
Section A4 is entitled "Anchor Rods and Threaded Rods" and permits A449 of any diamter. What is the technical definition of a "threaded rod"? My bolt is a threaded rod with a washer welded in the middle of it. It ends up with two nuts, one top and one bottom, with the washer in between two of the plies. Can I use this provision to get out of the A3 provision? Is there somewhere in the Spec or otherwise that technically defines a "threaded rod" and/or the uses of a "threaded rod"?
Also, my connection is to a cold-formed member. The 2001 Cold-Formed Spec allows threaded rods, but for diameters less than 1/2" ???!!!?? Does this deep-size the idea?
Considering that the bolt shear and uplift doesn't control by about 8x, I feel the need to wade through the dogma somehow and come up with a justification for this better and safer connection.
Any help would be greatly appreciated.
DBD
