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Slip critical joint

A slip-critical joint, from structural engineering, is a joint which relies on friction (rather than shear or tensile strength) to hold two things in place.

The most common slip-critical joint is where a girder meets a larger beam. Typically an angle plate joins the two. One beam is welded to the angle plate, the other has holes which are generally oversized or slotted. The bolt through this plate doesn't actually take the load as a shear joint or a bearing joint, it simply creates normal force and therefore friction between the two steel faces.

The joint ensures that the load is on the structural members and not on the bolt, so it creates a more efficient loading condition.