Demolition of Fire Damaged Structure

[kxa]

Are there any guidelines for demolition a steel frame structure that has been damaged by fire. The second floor girders and columns are sagging/bent and need to be removed. The first floor girders and coulmns are fine. All wood floor beams are damaged and are to be removed.

The client does not know what he will build on the first floor yet. To remove the second floor column, I am thinking ahead and proposing that they cut them off at least four (4) feet from the fist floor level for possible splicing in the future. Any thoughts?

Thanks,

 

[Ron]

kxa...that's probably a good idea. You will need to check and make sure that the columns are not damaged. Lack of deformation does not necessarily mean no damage when fire is involved.

If the columns were painted and the paint is not blistered, you're probably OK. If blistering of the paint occurred, check hardness in the field to make sure you didn't get quenching when the fire was doused.

If the columns are not painted, I would check the hardness in a vertical traverse to check the consistency.

 

[kxa]

Thanks Ron. The structure is about 70 years old with riveted connections and the steel was never painted. In fact, it has a lot of rust that the in some areas they are peeling as much as 1/4" thick. There is steel plenty of steel left I think sandblasting should clean that up. What is the best way to do a hardness test?

 

[dik]

You also might check with your building department to confirm/verify that you can construct on the same footprint...

Other than corrosion issues, if the steel is that old, there's a good chance that it has not been affected if no visual damage bearing in mind that it was likely designed for fy of maybe 30ksi or less; it is also possible to remove samples and have them tested.

 

[Ron]

kxa..you can use an Equotip portable hardness tester, but you need to be sure that the outer surface that might be carburized is removed by sanding. Usually no more than about 50 mils needs to be removed.

 

[JAE]

Ron, your range of knowledge continues to surprise me. Good to see you around here a bit more.

 

[Ron]

JAE...Thanks. That's very kind of you. I feel very fortunate in my career to have been exposed to lots of different things. It makes me enjoy it every day.