notching a PSL post

[hapunaterp]

Hello -
My question is regarding the analysis or calculations required to determine how notching a PSL post to take a 1 3/4" x 14" LVL beam changes the compression and bending strength of the PSL. Notching a post at the top in order to seat a girder beam is a typical practice but I have always been hesitant to notch a post along its height, say 3' or so from the top and maybe 6' from the bottom (approximately 10'+ tall post). I am cutting out a part of the cross section of the post but I am filling it in with the LVL beam. The question I have, though, is how do I quantify how much this has weakened the post? There will be loads applied vertically (gravity, bearing from beam) and laterally (wind). Thank you very much -

 

[mike20793]

I assume the post is taking load at the top of the post and at the LVL. Is it close to failing if you use the reduced cross-section of the post for the total loads? Maybe try using the reduced section for the loads above the LVL and the full cross-section for the loads below the LVL (with proper eccentricity on the post). Is it a square post? Is the LVL bracing the the strong axis or weak axis?

 

[hapunaterp]

Using the reduced cross section does not result in failure and the LVL is providing bracing about the weak axis.

 

[KootK]

Per NDS code, I don't think that you can have a notch in the middle third of a flexural member. I'm not even sure that disregarding the width of the notch would suffice as it's a stress concentration / fracture mechanics thing.


I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[TehMightyEngineer]

What KootK said, that's a stress concentration and it takes no consideration if they accidentally over cut a bit or otherwise made the notch worse.

I've only notched posts for beam seats at the top of the post away from bending stresses.

Maine Professional and Structural Engineer.