Uneven level of hooking loop post concreting long span girder highlighted in red

[vc00076]

Uneven level of hooking loop post concreting long span girder highlighted in red.

The rebar for the hooking loop can be seen in the 2 pic.

So basically these uneven level of hooking loop may cause high risk during beam launching/ transfer from casting yard to construction site. Any suggestion would be very much helpful on how to overcome this problem or suggest any article/ research information on this small detail. Thank you -vincent

 

[Valmiki]

The simple and very effective way to retain the lifting hook in same level, before casting check the hook top level w.r.t reference level from Bench mark at site and during concrete of girder check the hook level should retain same staff reading.
Hope my suggestion works to solve practical problem.

 

[HockeyPuck]

vc00076 It is a very astute observation on your behalf to note that you have a potential problem. Your concern is the likelihood that, during the lift, given the potential for non-uniformity of the contact surfaces between the rigging and the lifting loops, that you could over-stress the lowest-contacting loop, and/or that the higher loops might not be fully contacted & engaged, right? And this is not a small girder either judging by height of the rebar cage in the lower picture....well done on your observation!

The fabricator definitely has a difficult predicament to solve: Given the high stresses involved with the lift and the fact that the lifting loops are round, developing a customized incompressible "wedge" to insert below the loops that won't provide some sort of undesirable point load on any of the loops may not be achievable. All 3 loops (or 6, in this case....) need to act in unity during the lift - The fabricator needs to solve this problem. And, not only will the solution be needed in the fabrication yard to move the girder around, but the erecting subcontractor will also need to be aware of the condition and potentially use the same solution during beam erection. Great observation - Please let the community here know how you went about solving the issue - Cheers!!

 

[vc00076]

Yes sir spot on ! It's a bh concrete girder spanning around 50m to 60m.

Saw something was not right during inspection. Google could not find any data/details on uneven level of lifting loops.

Thank you for the reply and really appreciate your expertise as i am still very fresh to bridge construction.

Best regards from Malaysia !

 

[vc00076]

vc00076 It is a very astute observation on your behalf to note that you have a potential problem. Your concern is the likelihood that, during the lift, given the potential for non-uniformity of the contact surfaces between the rigging and the lifting loops, that you could over-stress the lowest-contacting loop, and/or that the higher loops might not be fully contacted & engaged, right? And this is not a small girder either judging by height of the rebar cage in the lower picture....well done on your observation!

The fabricator definitely has a difficult predicament to solve: Given the high stresses involved with the lift and the fact that the lifting loops are round, developing a customized incompressible "wedge" to insert below the loops that won't provide some sort of undesirable point load on any of the loops may not be achievable. All 3 loops (or 6, in this case....) need to act in unity during the lift - The fabricator needs to solve this problem. And, not only will the solution be needed in the fabrication yard to move the girder around, but the erecting subcontractor will also need to be aware of the condition and potentially use the same solution during beam erection. Great observation - Please let the community here know how you went about solving the issue - Cheers!!

Would you sketch the customized incompressible wedge to insert below the loops as i cannot picture what it looks like .