Lifting Beam
Lifting Beam
(OP)
I've a lifting beam that I'm trying to design. The lifting beam is 30ft in length, which utilizes a S 10x25.4, the top lifting lugs are 15'-0'' apart located centrally and at the bottom there a T section welded with holes spaced 1'-0'' O.C for lifting. I want to design the beam for one point loading, two point loading, three and four point loading. When I have just one load smack in the center I understand that the unbraced length is 15ft. When I use a two point load with loads placed atleast 8ft apart upto 28' apart, the unbraced length is 28ft. But when I use a three point load with loads spaced 8ft in b/w them max., I've one load say 1ft from left end, second load 14ft and third 28ft, in this situation will the unbraced length be 14'? or the distance between the end support which is 28'? .....similary when I space a 4point load spaced 8ft each will the unbraced length be 8ft? since there is load attached at the bottom and might help against lateral axis movement? Please respond Thanks






RE: Lifting Beam
RE: Lifting Beam
RE: Lifting Beam
RE: Lifting Beam
RE: Lifting Beam
The only lateral restain is the lift load itself in a multi span support, for example is a 30ft beam with 15ft lugs has lift 28apart, the Lu of the beam is 28, but for a multisupport beam which has lift say every 14ft, can the lift load acting vertical be considered as lateral restrain itself, there will no other lateral restrains in a lift beam
RE: Lifting Beam
That's why I refer to testbooks that tell you how to determine, or can you count on the lifted weight itsself as restrain/support.
Maybe I was confused over this issue. A sketch will help.
RE: Lifting Beam
I've attached a lifting beam loaded as shown, just tell me what is the unbraced length if you can.
RE: Lifting Beam
RE: Lifting Beam
RE: Lifting Beam
Thanks
RE: Lifting Beam
RE: Lifting Beam
1. AISC Engineering Journal 1991 4th Quarter, "Design and Construction of Lifting Beams" by David T. Ricker
2.ASME BTH-1-2008 Design of Below-the-Hook Lifting Devices
3. ASCE Structural Design and Construction Periodical May 2008 containing several articles by David Duerr.
I think the Ricker article has good information, however, some of this is superceeded by the ASME standard. One of the Duerr articles goes through a design example using the ASME code.
I thing the ASME standard uses an approach similar to AISC 9th edition (ASD) but applies factors to increase the factor of safety. Some parts similar to the AISC 13th Edition (2005 Specification) are also included.
It is a full design specification.