Anchor bolts of A320 steel

[J1D]

This might be an obsolete topic about steel grade for anchor bolts.

In the current project, it is advised to use ASMT A320 Grade L7. Reason for that is for cold temperature application and high steel strength. But at the same time, the price to pay is the deeper embedment into concrete and possible ductility loss.

We used a lot of A307 anchor bolts before (also in cold temperature enviornment). Is there any adverse effect using A320? Thanks for comments.

 

[structuresguy]

I would be looking to use ASTM F1554 Gr 105. This is the standard AISC recommended spec for anchor rods (with Gr. 36 and 55 also spec'd). In this case the Gr 105 would be very close in tensile strength to the L7 rod. But the L7 rod is not specified for anchor rod use specifically. It is more of a pressure vessel flange bolt spec.

Also, many suppliers make F1554 Gr 105 spec meet teh Charpy S5 spec for low temperature ductility. I would contact Portland Bolt. I believe they have a low temperature rated F1554 Gr 105 rod available.

 

[structuresguy]

Oh, to answer the other part of your question, only you can decide if the higher strength rod is worth the extra foundation depth and base plate detailing. I usually go to Gr 55 rod if I have large moments, but generally not as high as Gr 105, simply from an embedment depth concern. THe footings simply get too thick, in order to develop the tensile forces needed, when used in groups.

 

[J1D]

Thanks Structureguy,

You're right F1554 Gr 105 is about same strength as A320 Gr L7. F1554 Gr 55 (with Fy=55ksi) looks better for me if it suits old temperature as well.