I have used a theoretical model to study such a case using FEMAP. The deck is subject to uniform pressure.
To the right of this post is displayed the first bucking mode. This corresponds to the load case and boundary conditions used. It can be concluded that the structure is safe as regarding buckling. A different loading will change the eigenvalue and location where the instability will occur firs.
For more details on this study please leave a comment bellow and I will answer asap.