 In structural analysis, this bending failure is called a plastic hinge, since the full load carrying ability of the structural element is not reached until the full cross-section is past the yield stress.It is possible that failure of a structural element in shear may occur before failure in bending, however the mechanics of failure in shear and in bending are different.Moments are calculated by multiplying the external vector forces (loads or reactions) by the vector distance at which they are applied.