AS4100 spreader beam and column end restraint requirements

[geopat69]

Hi.

For the AS100 steel code, it requires that the ends of compression elements be restrained inplane and restrained out of plane....which is understandable. Normally, the ends of the column are checked to see if there is a load path to resist 2.5% of N* in the out of plane or inplane directions. Presumably the code includes this requirment to ensure the column does not destabilise under the action of the external load.

However, how can this philosopy be applied to a spreader beams which have considerable axial load from the slings attached to it.?? I refer to a typical/common horizontal spreader beam with triangulated slings to cause compression in the spreader beam.

Applying 2.5% in the out of plane direction ...has no load path (the beam would spin around!)...and thus does not comply to AS4100 where the ends of members need have 2.5% force resistance.

One school of thought is that the tension of the slings take on the role of restraining the beam? But i cant quanitfy this!


Any help is appreciated

 

[Settingsun]

Probably not required because the rotation has no ill effect. The load direction follows the spreader orientation so it's effectively pin-pinned regardless.

I'd check against a directly relevant code such as the US ASME "Below The Hook" code.

 

[human909]

I recently designed a couple spreader beams with AS4100 and the relevant lifting codes (forget which one). Yeah you just use pin-pin assumption.

The end of the compression member does not sway with respect to the load so in the reference frame of the beam and the load it is a pinned connection.

It likely doesn't need to be said but DO consider the eccentricity of the compression load.

 

[PersonalProfile]

The following was previously posted by others:

The basic problem was explained in detail in a copy of "Steel Construction" (Journal of the Australian Institute of Steel Construction), Vol 23, No 2 May 1989. Paper by Drs. Dux and Kittipornchai, "Stability of I-beams under self weight lifting".

In their conclusions the authors state :

The paper has investigated the stability of I-beams under self-weight lifting, when members are usually in their most slender state and when elastic flexural-torsional buckling forms an important design consideration. Existing classical and other published buckling solutions are not usually applicable...

An alternate reference (predating the 1989 paper, and not quite as detailed) is a paper by the same authors to the First National Structural Engineering Conference, Melbourne Australia, 26-28 August 1987. "Buckling of Suspended I-Beams".

https://www.eng-tips.com/viewthread.cfm?qid=38270