Aluminum Lifting Lug Design References 2

[starcasm]

Hello All,

I have an 8' x 8' platform I am designing with 6061-T6 aluminum channels, square tube perimeter, and diamond floor plate. The platform is not designed with support posts. It will instead be lifted and placed onto an existing ledge support on all 4 sides, like a cover. The assembly weighs less that 500 lbs total.

I have to design lifting lugs at the 4 corners of the assembly for hoisting and rigging. I am aware of ASME BTH-1, but that is for steel lifting lugs. Does anyone have a reference to aluminum lifting lug design? Or shall I use the ASME BTH-1 and apply the proper allowable stresses for 6061-T6 and appropriate safety factor? Just looking for some guidance.

I understand the load is light for what I plan on detailing. But the customer requires PE stamped calculations. I would like to reference something that makes sense.

Thank you in advance for your replies.

Daniel

 

[MikeHalloran]

Do be sure that the whole thing assembles with drive rivets or Huckbolts or some other cold fastener, or you account for the localized annealing associated with welding aluminum.





Mike Halloran
Pembroke Pines, FL, USA

 

[JStephen]

For lack of better information, I'd probably use ASME BTH and reduce by the ratio of yield or tensile stress. With that kind of weight, you should be able to apply an extra-generous factor of safety and still come up with lugs that are ten times oversized using typical construction. (IE, wouldn't one 1/4" bolt in the middle support the whole thing?)

 

[starcasm]

At MikeHalloran:
Thank you for the reply. The fabricator has already been selected and has experience with welding aluminum. I am checking their preliminary design to make sure it works. I am aware of the lower allowable stresses for welded aluminum in the HAZ, referencing the Aluminum Design Manual. Again, the loads this thing is going to see are small.

At JStephan:

Thank you for the reply. There is always a better way to do it. But the quantity and location of the lifting lugs have already been agreed upon between the customer, the fabricator, and the other engineer who went out there. 4 lifting lugs is over kill but there are not enough hours in the job to argue over it. I am giving them what they want and leaving it at that.


Daniel

 

[JStephen]

Oh, I wasn't suggesting you use just one bolt in the middle, just pointing out how oversize actual lugs are likely to be.