Frictional behavior

[esi_opensees]

Hello,

How can we specify a shear stress limit (tau_max) so that, regardless of the magnitude of the contact pressure stress, sliding will occur if the magnitude of the shear stress reaches this value?
A reasonable upper bound estimate for tau_max is sigma_y/sqrt(3) where sigma_y is the Mises yield stress of the material adjacent to the surface.

In other words, how can we monitor the bond-slip issue for a composite section?

Thank you.