Reply To: contact between two perpendicular shell plates

[Jim Day]

I suggest that flange and web share nodes at their juncture even though it means there's some slight overlap of material at that juncture.     *CONTACT_AUTOMATIC_SINGLE_SURFACE would only be needed if deformation were extremely large, such as would occur if the section buckled.

If that doesn't help, provide an image that illustrates the bad behavior.