Crane Column Cap Plate Material Grade
Crane Column Cap Plate Material Grade
(OP)
Cap plates on columns that support runway girders should be flexible enough to allow the ends of the girder to rotate. (pinned ends)
This means, the plate has to be thin enough to prevent yielding the extreme fiber so it always remains in the elastic range...or so I believe. Would any of you bump up to grade 50 plate material in order to not have an overly thin (<3/4") cap plate? Grade 50 is less ductile, but if its kept in the elastic range I'm not sure it'd be a problem.
You can easily meet all normal girder deflection requirements and still have an end rotation on the order of 0.005 radians.
This means, the plate has to be thin enough to prevent yielding the extreme fiber so it always remains in the elastic range...or so I believe. Would any of you bump up to grade 50 plate material in order to not have an overly thin (<3/4") cap plate? Grade 50 is less ductile, but if its kept in the elastic range I'm not sure it'd be a problem.
You can easily meet all normal girder deflection requirements and still have an end rotation on the order of 0.005 radians.






RE: Crane Column Cap Plate Material Grade
Dik
RE: Crane Column Cap Plate Material Grade
RE: Crane Column Cap Plate Material Grade
RE: Crane Column Cap Plate Material Grade
Therefore, you have to cantilever out your cap plate, which has to bend with the girder. All of this is standard crane construction in AISE, DG7, CISC,...they say to make sure the cap can sustain the rotations, but give no guidance on fracture.
If anyone has access to Fisher's paper on cap plates from the early 2000's let me know.
RE: Crane Column Cap Plate Material Grade
RE: Crane Column Cap Plate Material Grade
For lighter duty cranes with the bolts inside the flanges, I think leaving the bolts loose is good practice. The note was "finger tighten, back off 1/4 turn, and provide a lock nut". For heavy cranes, we used to do a rocker detail with the runway girder end plates bearing and a gap under the girder flange. A similar detail is shown in the CISC runway guide. A caution though, in some facilities, that type detail can lead to corrosion problems.
RE: Crane Column Cap Plate Material Grade
I'd recommend that design should ensure that stress remains well below yield.
Usually a higher grade steel will have limited, if any, increase in fatigue resistance.