F1554 vs A307 Anchor Bolts

[StructuralHokie08]

I have searched the forums and could not find a very straight forward answer. We had designed for a 7/8" A307 anchor bolt and our customer wants to use an 3/4" F1554 bolt. In searching for the answer I would think the answer is no, they would need to be the same size because they are just about the same strenght. Is this a correct assumption?

Thanks.

 

[CoryPad]

Are you talking about ASTM A 307 Grade C and ASTM F 1554 Grade 36?

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[StructuralHokie08]

Thats what I believe, but the only designation I have is A307 and F1554.

 

[CoryPad]

The information you have is inadequate. If you are talking Grade C and Grade 36, they are essentially identical. Note - ASTM A 307 Grade C is superceded by F 1554, so there really is no reason to specify A 307 Grade C on a new design.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[StructuralHokie08]

That is what I had figured. Thanks for the answers.

 

[hokie66]

If elongation of the bolt is important, remember the size is what counts, not the material strength.

 

[HeviiGuy]

elongation of the bolt is always important. If there is no elongation, there is no clamp load and thus the joint remains loose.

Ciao,

HevïGuy

http://www.heviitech.com

 

[hokie66]

HeviiGuy,

"Always" is a very strong word. There are instances where clamping force is not an issue. Take the case of sign posts with nuts above and below the base plate. Elongation would affect deflection, but would not loosen the joint.

 

[HeviiGuy]

Foregoing resistance to shear loading, the basic function of any threaded fastener is to develp a clamp load. Preloaded threaded fasteners act as stretched springs. Their normal tendency is to return to their unloaded length. This is the mechanism behind clamp load.

Even if clamp load "isn't an issue", when a nut is run down the inclined plane of the fastener's thread, and friction constituents of the joint are overcome, the fastener does indeed stretch (hence "elongation") -even in the aforementioned sign post example where the grip length is relatively miniscule.

Ciao,

HevïGuy

http://www.heviitech.com

 

[hokie66]

Thanks for the lecture, but there are occasions in structures when we want the bolts to slip, and a clamping force is counterproductive. Sometimes we intall them snug tight and then back off.

 

[HeviiGuy]

Interesting. Why not simply use a dowel if it's okay for the bolt to remain loose?

Ciao,

HevïGuy

http://www.heviitech.com

 

[hokie66]

Because you want it to stay in the hole. One example is the connection of a wind column at the end of a portal frame building to the end portal at roof level. You want the wind column to resist horizontal load only, so you allow the portal rafter to deflect by using slotted holes and bolts that are not tightened. Horses for courses. I am all for tight bolts, but my point was that "always" is not correct.

 

[Dinosaur]

F1554 is good material. It comes in three grades; 36, 55 and 105. I would want the same diameter rod as the original design, but thqat is negotiable if they are asking to substitute grade 55 material. Good Luck.