In computational fluid dynamics (CFD), complex surfaces that are not completely solid can be modeled using porous or permeability media. In the actual world, examples of such things include windbreak fabric structures, wire meshes, perforated facades and claddings, louvers, tube banks (stacks of horizontal cylinders), and so on.
In RFEM, you can simulate a scaffolding tube joint (butt joint with a stub) by a nonlinear member release of the "Scaffolding" type. The joint considers moment resistance dependent on compression forces existing between two outer tubes, and the stub also has certain moment resistance based on its bending resistance.