Utility anchor for precast structure
Utility anchor for precast structure
(OP)


So the capacity of these anchors in shear is quite high. If you get the appropriate lifting hooks for the weight, the hook actually cannot fit the pocket! Has anyone encountered this before? For example the 8CA18 from CONAC. According to this chart it can handle up to 20,000 in pure shear. I specified 4 of these lifters on a 60,000 lbs structure (15,000 lb each lifter). The contractor rented a 5/8" chains with hook that is capable of lifting up to 18,000 lb. The hook will not fit the lifting pocket. The only chain and hook that can fit in the pocket is rated for only 12,000 lb.
Have you encountered this before? What can you put between the lifter and the hook? Is there some kind of strap or cable you can loop through the lifter?






RE: Utility anchor for precast structure
I'd use a short endless sling to go from the hook to the lifter. Also, unless you're specially rigging it you're likely only going to distribute the load to 2 or 3 lifters so you might actually not be getting the full OSHA safety factor; slings will help with this as they stretch some.
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
https://www.facebook.com/AmericanConcrete/
RE: Utility anchor for precast structure
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
https://www.facebook.com/AmericanConcrete/
RE: Utility anchor for precast structure
RE: Utility anchor for precast structure
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
https://www.facebook.com/AmericanConcrete/
RE: Utility anchor for precast structure
RE: Utility anchor for precast structure
Whenever I need to utilize a lower concrete strength than tabulated I do one of these: If I'm in a hurry I'll probably just specify a lifter that has tabulated data for the strength I'm at. If I have the time, I might run the appendix D failure modes, determine which one controls, and find a ratio of the strength change between the two concrete strengths (as you indicated); this is the recommended method by the lifting device manufacturers. Finally, if I'm really backed into a corner I'll just specify that they need to cure it until they hit the required stripping strength.
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
https://www.facebook.com/AmericanConcrete/
RE: Utility anchor for precast structure
Mike McCann, PE, SE (WA)
RE: Utility anchor for precast structure
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries
https://www.facebook.com/AmericanConcrete/
RE: Utility anchor for precast structure
Thanks..
Mike McCann, PE, SE (WA)
RE: Utility anchor for precast structure
RE: Utility anchor for precast structure