Wood Stress Wave NDT question

[BR0]

Hi All,

I am working on an existing building with about (100) 5.25x15 - 24F-V4 glulams. Many have deteriorated in one area due to a waterproofing issue. Many of the glulams have damage that is a bit of a grey area that visually and by sounding is not severe but there does seem to be some reduction. This deterioration is in the compression zone.

The roof is part of a driving range platform and 2/3s of the roof has a concrete overlay and the other 1/3 has a membrane roof. The roof leaks at the junction.

In the NDS this glulam has a Tension Zone in Tension - Fbx+ = 2,400 PSI and a Compression Zone in Tension - Fbx- = 1,850 PSI. It doesn't say explicitly what the Compression Zone in Compression is, but I believe it is implicitly Fbx = 2,400 PSI.

The reason this is of interest is that using Stress Wave NDT and comparing the stress wave transmission times between sound wood and decayed wood there is a correlation to % reduced capacity can be inferred. A reference that goes into this by USDA is Stress Wave Timing Nondestructive Evaluation Tools for Inspecting Historic Structures.

https://www.fpl.fs.usda.gov/documnts/fplgtr/fplgtr....

I was wondering if anyone has ever used Stress Wave NDTs to determine a reduced capacity and if they have any additional sources for the correlation.

I appreciate any help you can provide.

 

[phamENG]

Can't speak to the Glulams, but that's some nifty assessment tech. I'm interesting in hearing more about that.

 

[BR0]

It is pretty nifty. We have used the consultant who has the equipment before for a similar type of evaluation, but never with a reduced material capacity given. It was usually to identify internal degradation that wasn't visible or identifiable from the outside. We used it to determine if the section loss was significant. However, on these glulams there are a lot that do not seem to have much damage but appear to have some reduction.