Lloyd's Code for Lifting Appliances in a Marine Environment

[Andreas Mavridis-Tourgelis]

Hello. I would like your help with respect to :
Chapter 4 section 2 Paragraph 2.24.5 of the LATE.
There in case of loading of a flange which is connected to a main structure through a circularly patterned bolted joint states:

Can someone explain why it subtracts the load due to tension of each bold from the load due to bending moment?
In my opinion it (the term H/N) should be added for the most heavily loaded bolt!
I am trying to figure out the justification behind the formula as my organisation needs to design by that code.
By subtracting the tensile stress due to tension don't you underestimate the possible maximum load for the most heavily loaded bolt?

Thanks in advance

 

[D_UK]

Andreas

This calculation is for a crane slewing ring, so naturally the direct load is compressive. In the general case the sign would reverse if the load on the group is tensile.

David

 

[Andreas Mavridis-Tourgelis]

Thank you very much

That was my thought too. It was sent to us by a subcontractor and the calculation didn't many any sense.
But nevertheless i needed to check before i make my report.

Thank you again

 

[chicopee]

D UK, when stating crane slewing ring are you referring to the turntable ring?

 

[D_UK]

Chicopee

Lloyd's refer to this specifically as the "slewing ring bolting" calculation, which I guess might also be called the turntable ring.

The calculation is derived by taking the bolts as distributed around their pcd and taking the tensile/compressive and bending on the resulting tube.

David

 

[TimSchrader2]

Hello
The design axial load is the vertical load from dead wieght of crane and the load lifted. This is assumed as equally distributed across the slewing bearing. SO, on the tension side of the slewing ring from the moment load the axial load will decrease the tension load in the Bolts.

The axial load does reduce the moment rating of the slewing ring bearing by a small %. As on the compressive side it adds force to the ring.

If this is a SOLAS (Safety of life at Sea) crane there are additional safety factors that must be applied. But that is another subject entirely.