Cantilever Beam Question

[mjordao]

I'm working on an existing steel building where the owner wants to add a new generator on the roof and I'm checking the existing girders. There are 6 bays and the steel girders cantilever past the columns and are spliced with intermediate girders. I can't find any information in text books about this type of design. I'm having trouble with the negative moment at the columns and the lateral torsional buckling. I'm assuming an unbraced length for the bottom flange of the entire distance between the columns. Does anyone know if I can take instead the length from the support column to the inflection point in the moment diagram? Are there any publications out there that deal with this situation? Thanks!

 

[slickdeals]

@BA,
Do you have any comment on

For the column to be pinned-pinned, I think that the W6 beam's web will have to be able to resist 2% of the compression in the column without significant lateral displacement. Right?

We are Virginia Tech
Go HOKIES

 

[BAretired]

@slick,

Sounds reasonable to me. It is difficult to say how much of the beam web participates in the column extension through the beam. Maybe 4" is about right. If in doubt, I would add stiffeners.

BA

 

[ToadJones]

Might be of interest....

 

[slickdeals]

Same document as the one I posted on 7 Jul 10 10:39

We are Virginia Tech
Go HOKIES

 

[ToadJones]

Oops...
Must read past that.
Sorry Slick.