Jacking Design

[TTMK]

I just finished a jacking design and received a comment regarding local flange bending with a sheet of documentation from a unknown source. I looked back at the AISC Steel Construction Manual (13th ED) in section J10 (Flanges and Webs with concentrated forces) and noticed some literature that disagrees with the comment. 16.1-355 states that "Single concentrated forces may be tensile (such as those delivered by tension hangers) or compressive (such as those delivered by bearing plates at beam interior positions, reactions at beam ends , and other bearing connections). Flange local bending applies ONLY for tensile forces."

SO based on this language from the AISC Manual it is MY understanding that Flange Local Bending does not need to be checked for my jacking design (since it is going to be a compressive force delievered by a bearing plate at interior positions and beam ends). I did check web crippling and yielding.

Does anyone have any input to what could validate this comment or do I have a pretty good leg to stand on to argue the comment?

 

[MiketheEngineer]

How is it being jacked?? Flange loads might need to be checked based on what you are doing??

 

[paddingtongreen]

Are you considering that any of the load is supported by the flanges? If so, you must address the effect on the flange. If, on the other hand, you consider it supported by only that area above the web and fillets there is nothing to check.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[BAretired]

Unless I misunderstand the situation, local flange bending must be checked for any concentrated force acting normal to the flange. Whether the force is tension or compression is irrelevant. Either way, it produces local flange bending.

BA

 

[TLHS]

If you've got a bearing plate that can span all the load into the web, and your web can take the load without buckling, you should be fine.

If your load path involves bearing directly onto the complete underside of the beam your web stiffness in comparison to the flange stiffness is going to ensure that basically all of the load goes directly into the web unless you install some kind of stiffeners. As long as your assumptions are based on that, you should be fine. If you've got a torsional moment of some sort, or an uplift, or anything else that might throw part of your connection into tension then the situation changes.

 

[structSU10]

AISC 360-05, within the commentary for flange locaal bending:

"Although this deformation could also occur under compressive normal forces, it is customary that flange local bending is checked only for tensile forces (because the original concern was weld fracture). Therefore it is not required to check flange local bending for compressive forces."

Earlier on in this section, they discuss how this provision was initially intended for moment connections to ensure the flange is rigid enough as to limit local deformation, and preclude the chance of flange local buckling.

It does state it is not required to check for flange local buckling, not neccesarily that it is not applicable.