lifting points - 3 sided culver

huangyhg

lifting points - 3 sided culvert
hi everyone,
i'm designing a 3 sided, precast culvert and want to make sure i design the lifting attachments correctly.  anyone got a good method already established to do the calculations to pick out the the correct lifting points/locations?
if possible, i would like to do this via hand calculations.  that said, if necessary, i could pick up a 3d modeling pacake like risa-3d.
thanks a lot!
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1.  locate the center of gravity in 3 dimensions.  the crane hook will be directly over that location.
2.  determine a reasonable length for the lifting cables, realizing that the closer to vertical they are the better.  maximum crane size and hook height will also impact this.
3.  determine the loads at each point of attachment.
4.  design your method of attachment.
many precast elements are lifted using a smooth eyebolt attached to each leg of the (4) lifting cables.  the eyebolt slips into a hole cast into the element.  the geometry keeps the eyebolt from slipping out of the hole.
  
ralph
structures consulting
northeast usa
if it's three sided, additionally, i would use a speader assembly to limit the picking forces to vertical only to the wall axis.
mike mccann
mmc engineering
mike,
it's unlikely that there would be significant lateral forces applied to the sidewalls, as the lifting lines would have to rise vertically until they cleared the top slab where they would then angle to the crane hook.
  
ralph
structures consulting
northeast usa
do you have a sketch what the culvert looks like??
i don't have a sketch yet.  i'm working the problem later this weekend.
thanks for the information.  this is extremely helpful.
i agree with msquared 48, use spreaders to give vertical lifting points and then place the lifting points above the vertical side walls to give greater embedment.
are you sure there is an integral top slab? 3 sided culverts can be set on a poured footer and floor slab or can have a separate precast top slab that is installed after the 3-sided culvert is installed.
(see attached file)
in other words, the culvert might be "u" shaped and the lifting eyes could be mounted directly into the top end of the side walls. (would still recommend spreader bars or struts though) remove the eye bolts and then set the top slab "lid" in place.
if cvg is correct then you definately need spreader bars.
upside-down "u" shaped culverts are common.  a lot of inland wetlands folks like them because the leave the streambed undisturbed.  i watched one get installed near my home - they cast a footing along both sides of the stream, then dropped the culvert sections onto the footing.
  
ralph
structures consulting
northeast usa
yeah, this will be an "upside" down u shaped culvert, set onto poured footers.  the state wants to keep the natural streambed for supporting local trout populations.
i've integrated anchors to the top and sides of the culvert.  definitely going with a spreader bar to keep the lines vertical.
thanks for the help!