Lifespan of a PEMB

[structuralengr89]

Does anyone know the typical lifespan of a PEMB constructed in the 1970's? Any backup documents on this?

I'm doing an inspection on a PEMB constructed in the early 1970's in a coastal area that has quite a bit of corrosion of the metal panel walls, metal panel roof, etc. I think it needs to be torn down, but looking for any info that says PEMB's typical last about X years.


Thank you!

 

[WARose]

I checked several PEMB references I have and there was no answer. The number I've typically heard for most steel buildings is 50 years. I'm not 100% sure what that is based on. The return period for wind loading is typically 50 years. For a lot of cranes, the classes are based on X amount of applications over 25-50 years. You'd think there would be a fatigue limit for live load application in certain situations. (A lot of cycles can pile up in 50 years.)

In your case, you'd have a special circumstance due to the corrosion.

 

[structuralengr89]

Thank you WARose!

 

[atrizzy]

The metal panel roofing and siding can be replaced easily enough. How's the primary structure holding up? What about the girts?

 

[structSU10]

What atrizzy said should be the focus. PEMBs generally are designed right to the limit for the main structure. If there is significant corrosion of the purlins, girts, or moment frames, they would likely need reinforcing/repair or replacement.

I have use a ultrasonic thickness gauge to check steel thickness at corroded areas before, and its fairly reliable for spot checks.

 

[azogr]

That is good advice from atrizzy and structSU10. One thing I would add is that older PEMB's were designed a little more conservatively than modern day ones. The older buildings truly were "pre-engineered" for a variety of conditions so parts could be pulled off of a chart. Nowadays they are all computer designed uniquely for each project and are designed very tight.