Effective Buckling Length for Post Restrained at Midheight 2

[Maturin]

Can anybody tell me how I would determine the "K" value for a post fixed at it's base and laterally supported at midheight? The axial load is applied at the top of the post.

 

[miecz]

When I had the pseudo girder idea, I wasn't sure I believed it. But I couldn't find a solid reason to reject the idea, so I decided to post it, thinking that someone would convincingly trash it. I opened this thread expecting to read - "no way, blah, blah, blah..."

Instead, I'm left with the uneasy feeing that it may be correct. After all, if GA is infinite, then k is infinite, and that is obviously wrong.

The real reason for my post was to counter the idea of blindly accepting a computer result. If the psuedo girder approach yields K=2.35 and a software package gives K=2.7, I would use K=2.7.

 

[JAE]

...or 3 just to be sure.

 

[Maturin]

I agree computer results shouldn't be accepted blindly.

As I mentioned in an earlier posting the K=2.7 value could also be verified manually by considering the deflection diagram for a beam overhanging one support with a load applied at the tip, (from AISC Handbook Tables, Roark, etc.). The distance between max deflection and the tip is 1/2 the buckling length. The resulting K comes out very close to 2.7