Precast/Tilt-Up lifting anchors - Combined Shear/Tension

[530_3D]

I'll keep it short...half the hardware vendors and consulting engineers say combined shear and tension should be checked for lifting hardware, other half say it doesn't apply. Sometimes it controls.

Assuming its origin is in ACI Ch. 17, there is a disclaimer in the first paragraph of the chapter: "Safety levels specified are intended for in-service conditions rather than for short-term handling and construction conditions." There is also the 4:1 safety factor specified in OSHA 1926.704, which is further straying from ACI Ch. 17.

I feel comfortable not checking it when such a large safety factor is used for tension and shear capacities, and a recent check of an anchor using Ch. 17 calculations showed it passed when maxed out in tension and shear, but the catalog-listed capacities are more conservative.

Any precast or tilt-up folks able to weigh in?

 

[KootK]

I agree with your perception that it is uncommon to see folks checking combined tension and shear in practice in this space.

I can, however, think of no valid technical reason to justify that practice. Be they large or small, I don't believe that it is the intent of safety factors that they should compensate for undercooked design approaches.

I kind of feel as though the catalog purveyors lean into this a bit. "Here are some simplified design values that you are welcome to combine in more complex and penalizing ways if you wish". Wink wink.