Queries on Weld Strength

Where is the attached picture?

what material?

what type materials?

what size?

Briefly, you're going to need to figure the weight of the lifted structure + lifting impact forces as well as momentum forces due to twisting about a cable in order to properly design the welds and the lifting pads.

Materials? Yield stresses? welding electrode grade and types? static weights/loadings? number of pick points? What type of hollow tube, as in round or square or rectangular?

Frankly, you need to obtain a really good "lifting design" textbook as well as review the code requirements. Many municipalities today require that a qualified Professional Engineer design the lifting system, prepare the drawings and affix & sign his /her PE seal on the drawings, and finally prepare the actual LIFT PLAN. All of this is required because that have been too many lifting failures in the past, with quite a few fatalities.

Check online or request the Lifting Code requirements and regulation of both NYC and Chicago, some of the best in the world as well as the most stringent. Their respective building departments can assist you with your questions.

Good luck with your endeavors!

Signed,

CaptMoosie, PE/PhD

Civil, Structural & Environmental Engineer

Oh, I forget to mention some important factors regarding the static and dynamic loadings......don't forget the wind loads and ice/snow loads where applicable!