Underslung Crane Runway Beams 8

[dik]

Does anyone have a source for information regarding designing underslung loading of crane runway beams, in particular, references to lateral stability and lateral loading.

Dik

 

[Bagman2524]

Define underslung loading. It should be a matter of checking the weak axis of the member.

 

[BAretired]

Dik,

Between the prevailing building code and the data from the crane supplier for a particular crane, the magnitude of the loads are specified. I have some data, but it is pretty old. I believe this information can be readily found on the internet.

BA

 

[bootlegend]

You may want to check out "Allowable Bending Stresses for Overhanging Monorails" by Stephen Tanner, an AISC article from 1985.

The brace points for LTB becomes an issue.

 

[spats]

I remember have an old US Steel Handbook that gave a formula for allowable bending stess for an unbraced top flange based on the section being loaded below the shear center. Loading below the shear center has a self-righting effect. I will see if I can find it.

 

[Hemifun]

Two good references which I use are AISE Report No. 13 "Guide for the Design and Construction of Mill Buildings" and CMAA Spec. No. 74 "Specifications for Top Running & Under Running Single Girder Electric Traveling Cranes Utilizing Under Running Trolley Hoist".

 

[SKIAK]

Have you looked through AISC Steel Design Guide Series 7?

 

[PSwan]

You may want to check out this AISC steel tool I got off their website. (attached) Its old code, but may give some insight. You may want to check the site for a new code version if you are a member. I have designed many crane rails for aircraft hangar doors in the past. It was always difficult to get the S shapes to work in weak axis bending. Many times we would weld a C shape to the top (flanges down) to increase lateral stability. I think the 13th ed steel manual has properties for such composite sections.

-PSwan

 

[PSwan]

I guess you can't attach a file directly, here is the link

http://files.engineering.com/getfil...c72-b2d7-54400456ff9d&file=CraneBeam_v1_1.xls

-PSwan

 

[SKIAK]

Also, ASCE 7's section 4.10 "Crane Loads" provides some guidlines as far as impact, lateral and longitudinal forces.

 

[dik]

I've been through DG7 and 13, earlier, and have just picked up a copy of "Allowable Bending Stresses for Overhanging Monorails" and have a copy of the AISC spreadsheet from years back.

Spats:
If you can locate the info on loading below the shear centre, it would be appreciated.

I'm having a bit of a problem with the effect of the loading stabilising the beam and precluding lateral torsional buckling. My initial thoughts are that unsupported length is not an issue since any attempt to 'rotate' is resisted by the load. The only concern is the top flange buckling from the compressive loading.

Dik

 

[spats]

Dik,

I'll see if I can find it... will probably be tomorrow before I can respond back.

 

[BAretired]

Timoshenko in "Theory of Elastic Stability" treats lateral buckling of beams with loads at the upper flange, centroid and lower flange. He considers two cases for a simple span, load at midspan and uniform load over the entire span.

If you can find a copy of that book, it should give you a rough idea of the effect of the position of load on buckling capacity of a simply supported I shaped beam.

If you can give me the magnitude of L²GJ/ECw, I could give you an idea of the effect of positioning the load in each of those three positions.

BA

 

[BAretired]

Dik,

I was surprised to find that the book I mentioned can be downloaded at:

http://www.4shared.com/file/70018841/be932e19/Theory_Of_Elastic_Stability_Timoshenko.html

Check out Chapter 7.

BA

 

[dik]

BA... thanks for the link... I've got a copy of the book packed in a box... but this is a lot faster to find.

Dik

 

[dik]

Thanks, gentlemen...

Dik