Nail Shear Strength Test

ddawg16

Daniel...please correct me if I'm wrong....but this is how I remember it from my statics class........some 30 or so years ago....

Think of a torque wrench....the force you exert on the socket is the 'moment'...which is a function of the force on the wrench and how far away it is....

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Daniel Holzman

Moment and torque are identical. They are computed by multiplying the force on the arm by the distance from the arm to the pivot point, so if I have a 2 foot long torque wrench, and I apply 100 lbs of force on the end of the wrench, the moment (or torque) is 200 foot pounds.

The distance often must be computed between the centroid of the applied force and the centroid of the loaded point. For example, your hand may be four inches wide, if you push down on the end of the wrench the moment is computed based on the distance from the center of your hand to the center of the bolt.

In the case of multiple bolts, things get considerably more complicated, since each bolt is likely to be a different distance from the applied force, so each bolt sees different load. The key point is that each bolt sees a shear force, not a moment, so the actual force on a fastener is always resolved into a shear force except in the case of direct compression (hammer blow) or direct tension (pullout). From the point of view of the bolt, it doesn't know or care if the bolt load arises from direct shear of the framing member, moment on the framing member, or some combination of the two, the bolt always feels shear. Whether or not the bolt fails is entirely due to the magnitude of the shear, and the strength of the bolt in shear. This applies equally to nails, screws, lag screws etc.

Duckweather

Thank you. You do realize giving away your secrets may make some of us more dangerous. ("A little knowledge can be dangerous") Boston. I am in southern NH, (Brentwood), You're close enough for me to put you in my list of contacts.