New Southern Yellow Pine Values

[tolchijb]

Has anyone begun implementing the new design values for southern yellow pine? Based on the reading I have done, for bending spruce/pine/fir is now better than southern yellow pine. I am struggling with this demotion of SYP and am wondering whether SPF lumber will become the norm or maybe MSR & MEL lumber will become more prevalent. Any thoughts. FYI - I am in the midwestern US. I have attached some documentation for those of you not familiar with the change.

 

[Archie264]

To directly answer your question, no, I have not yet used these values and in fact this is the first I've heard of it so thanks for posting the information. I can't say I'm happy to learn of it, though.

 

[strucguy]

More information regarding this matter can be found at the following link.

http://www.southernpine.com/new-design-values.asp

I had a wood project the construction of which began in late March. When I contacted the building office about this change, he promptly told me to ignore it. So, always check with the building official on issues like these and document their response.

 

[briancpotter]

This article suggests younger trees being used as a source of lumber as a possible reason. I've heard the same thing from another engineer, that modern trees are able to be grown faster, but may not have the strength of old-growth trees:

http://www.prosalesmagazine.com/wood/rise-of-the-machines.aspx

Brian C Potter, PE

http://simplesupports.wordpress.com

 

[woodman88]

As the new values are based on what is leaving the lumber mills I would think it would be best to use the new values. But then I have not used any SYP for the last ten years.
See the attach for more information about why they are changing.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[efsinc]

It's my understanding that these new values are the result of a process parallel to the process that underlaid the significant downward adjustment of Douglas Fir allowable stress values in 1991 (which, coincident with a recession and the revenge of the spotted owl closing down old growth forests, created an opportunity for steel to make inroads into the southwestern construction industry.) Then, numerous samples of in-grade lumber, ie previously visually graded lumber were destructively tested. The new values more accurately represented the maximum stress that we ahold expect. As such, based upon destructive testing, it seems proper that these new values should be used.
I too have heard the thinking that the farmed fast grown lumber is at least a part of the reason.