Fire Damaged Anchor Bolts

[AZPE]

I have a town home project that was burned down by an arson after it was fully framed. I haven't been to the site yet but I know that they are going to ask. They will want to know if the anchor bolts are going to be salvagable. What issues would you expect from bolts that have been in a residential fire? I wouldn't imagine that the heat was very great, or at least not hot enough to alter the steel properties. I would guess that the bolts would be okay

Any thoughts/ideas/help would be appreciated.

 

[metengr]

Don't guess anything. The answer to your question depends on the anchor bolt material specification. Do you know what was specified, like ASTM A 325 or A 490 or some other designation? Are there any markings on the heads? Can you remove one or more anchor bolts for visual inspection for a side by side comparison with a new anchor bolt, and lab testing (if required).

Once you know the answers to the above questions, there are tests that can be performed to evaluate if the bolts have been altered as a result of exposure from the fire.

If I am asking these questions, you can bet an insurance investigator will ask them. I have been through these type of investigations on industrial equipment fires and explosions.

 

[EdStainless]

There are many possibilities.
-The bolts only got warm, no harm at all.
-The bolts got hot, but not real hot. This would temper them to a lower strength level, but all in all the properties wouldn't be bad.
-The bolts got real hot re-annealing or normalizing them. they will be weak and you don't know what the properties are.
-The bolts got real hot and they were cooled quickly as they were fighting the fire. They bolts could end up (depending on chemistry)hard and brittle.

Find the original spec a bolt. Have hardness tests done on all of them. If there is a lot of scatter I would lean toward cutting them all of and drilling and grouting new bolts.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[CoryPad]

In general, fires have temperatures around 1000 [&deg;]C. In general, steel fasteners for structural applications have temperature limits < 500 [&deg;]C. You may not be able to retain the anchor bolts.

Regards,

Cory

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

 

[AZPE]

Thank you for all your responses. The bolts are A307. Sounds like I am in a little over my head. I may need to defer to a construction materials testing company to determine if they are structurally adequate. What would I need to tell them to test for? Would they be able to cut a portion of the top of the anchors or would they have to remove the entire anchor?

Again, thanks for your help.