Bolt shear capability independent of preload?
Bolt shear capability independent of preload?
(OP)
I've recently heard of some testing that indicates that the shear capability of a bolt is effectively independent of the applied preload, for "normal" values of preload. The tests have been done with a bolted double shear joint, with the faying surfaces of the clamped members lubricated to minimize the clamping friction. They've found that varying the preload between 50% and 85% of yield has around a 1% influence on ultimate load capability.
I haven't thought it through yet, but on the surface, this doesn't make a lot of sense to me. Clearly, the body of the bolt is under combined tension and shear stress, and that should reduce the capability. Maybe it's the little bit of friction remaining between the plates, maybe there are some nonlinearities that are playing havoc with the linear lens through which I view the world.
Does anybody have any insight on this? I apologize, I don't have a reference for the testing.
--Tom
I haven't thought it through yet, but on the surface, this doesn't make a lot of sense to me. Clearly, the body of the bolt is under combined tension and shear stress, and that should reduce the capability. Maybe it's the little bit of friction remaining between the plates, maybe there are some nonlinearities that are playing havoc with the linear lens through which I view the world.
Does anybody have any insight on this? I apologize, I don't have a reference for the testing.
--Tom





RE: Bolt shear capability independent of preload?
RE: Bolt shear capability independent of preload?
ht
Go to page 47 and read from there.
RE: Bolt shear capability independent of preload?
I guess I need to look up the references cited there.
RE: Bolt shear capability independent of preload?
RE: Bolt shear capability independent of preload?
http://www.FerrellEngineering.com
RE: Bolt shear capability independent of preload?
http://www.aisc.org/content.aspx?id=4502