  An analytical model based on variational principles for a thin-walled
stiffened plate subjected to axial compression is presented. A system of
nonlinear differential and integral equations is derived and solved using
numerical continuation. The results show that the system is susceptible to
highly unstable local--global mode interaction after an initial instability is
triggered. Moreover, snap-backs in the response showing sequential
destabilization and restabilization, known as cellular buckling or snaking,
arise. The analytical model is compared to static finite element models for
joint conditions between the stiffener and the main plate that have significant
rotational restraint. However, it is known from previous studies that the
behaviour, where the same joint is insignificantly restrained rotationally, is
captured better by an analytical approach than by standard finite element
methods; the latter being unable to capture cellular buckling behaviour even
though the phenomenon is clearly observed in laboratory experiments.
