Admissible geometrical domains and graphic statics to evaluate constitutive elements of structural robustness

Structural robustness is related to the insensitivity of a structure to local failure, which is linked to the ability of force redistribution. Current approaches—probabilistic, risk-based, deterministic, and energetic—are poorly suited to inform the design of a structure at conceptual stage. Yet robustness issues must be addressed early in the design process, when interaction with the structural model is still feasible. This article explores how geometrical solution domains provide indicators that summarize the ability of a structure to redistribute load paths. Since geometric methods only build on abstract load path networks, directly connected to form and force diagrams, they suit well for early design explorations. This article presents two case studies, shows how geometrical domains provide qualitative and relevant constitutive indicators of structural robustness, and finally compares the results with indices of deterministic and energetic criteria currently proposed in the literature.