Rigid-Block Equilibrium (RBE) is a numerical approach that frames the equilibrium problem of rigid-block assemblies as an optimisation problem to compute possible internal and equilibrated singular stress states. The contact between blocks is considered to have a finite friction capacity, and the unilateral behaviour is modelled through a penalty formulation. In particular, the penalty formulation widens the standard admissible solution space of compressive-only forces by allowing for tensile forces to appear in potentially unstable regions.
The RBE objective function minimises the interface forces, whereas the constraints are linear functions enforcing the static equilibrium of the whole assembly. compas_rbe provides a base implementation of RBE. In compas_rbe, blocks are considered infinitely rigid and have infinite compressive strength. compas_rbe provides the necessary contact forces (i.e. compression, tension and friction forces) for the assembly to be in equilibrium under given external loads.