A stress magnification factor for plates with welding-induced curvatures

The fatigue strength of thin-walled structures can be reduced
significantly by non-linear secondary bending effects resulting
from geometrical imperfections such as axial and angular
misalignments. The welding-induced distortions can cause a
critical increase of the structural hot-spot stress in the vicinity of
the weld. Traditionally, the classification society rules for the
fatigue strength assessment of welded ship structures suggest an
analytical formula for a stress magnification factor 푘푚 for axial
and angular misalignment under axial loading condition.
Recently, the well-known analytical solution for the angular
misalignment has been extended to account for the curvature
effect. The present paper analyses the effect of non-ideal,
intermediate boundary conditions between fixed and pinned
ends. In this regard, the fixity factors ρ (with 0 ≤ 휌 ≤ 1 from
ideally pinned to clamped conditions) are introduced in order to
model the actual constraint on the rotation close to the ends.
Under tension, a non-negligible decrease of the 푘푚 factor is
observed in relation to the reduction of the fixity factor at the
welded end, while the fixity factor related to the loaded end has
a minor effect on the 푘푚 factor. Under compression, the
reduction of the beam end fixity factors results into lower
buckling resistance.