Friction springs in nodal supports.
Friction supports can be used to model the fact that a reaction component is dependent on another component. The horizontal component is for example dependent on the vertical component. When the friction force is surpassed, the support slips through resulting in large deformations.
Friction supports can be used for several types of structures. Nearly every support which isn’t rigidly connected to the surface on which it stands is subjected to friction.
Note: Friction can be inputted in one or two directions. It is not possible to define friction in all three directions since otherwise the "thrust" cannot be determined. When simple friction (X, Y, Z) is defined in two directions, the option Independent is available. This specifies that the friction in one direction is independent on the friction in the other direction. Composed friction (e.g. YZ or Y+Z) can be specified only in one direction.
Example of the usage - Scaffolding