Torsion in Underhung Crane Runway
Torsion in Underhung Crane Runway
(OP)
I am designing an underhung crane and currently have a cross section consisting of a built up wide flange and channel cap system. The channel has been provided for bending in the out of plane direction. However, I am running to the issue of resolving the torsional forces. The torsional stress could be potentially very high on this section and there doesn't really seem to be a good way to resolve the torsion as I am unable to attach anything to the bottom flange. Does anyone have any advice. Also, I have assumed that the torsional properties are similar to that of a wide flange for example J = sum bt^3/3. Would the torsional properties be much differen for this section?






RE: Torsion in Underhung Crane Runway
RE: Torsion in Underhung Crane Runway
I generally assume that the bottom flange has to take all of the side thrust loading and ignore torsion. Basically the same assumption made for top running crane girder design.
Be sure also to check the combined stress in the bottom flange from the local wheel loads. CMAA has a set of equations for this.
The reason I ask about how the beams are supported is that generally underhung beams are hung from hangers that allow the beams to sway somewhat. This reduces the torsional stresses.
RE: Torsion in Underhung Crane Runway
RE: Torsion in Underhung Crane Runway
RE: Torsion in Underhung Crane Runway
RE: Torsion in Underhung Crane Runway
there is a method in AISC for calculating the torsional properties of built up sections.
RE: Torsion in Underhung Crane Runway
http://www.integritycrane.com/docs/Design_20of_20M...
A wise to the matter opinion...
http://www.peo.on.ca/DIMENSIONS/septoct2004/Letter...
leaves it a 10% (but no code)
If I find something normative will add later.
RE: Torsion in Underhung Crane Runway
http://www.eng-tips.com/viewthread.cfm?qid=44818