The role of complexity in random element removal in statically indeterminate structures

Modern requirements on constructions impose that proper design strategies must be adopted in order to obtain a robust structure: in this sense, consequence-based design focuses the attention on the structural response to damage. The behavior of statically indeterminate structural systems under damage is non-linear because the load paths intertwine each other, even if each component behaves linearly. As much as the structural complexity increases, the presence of effective ways of carrying the load becomes crucial for the robustness of the struc- tural system under a damage process acting at random on the structure. In addition, the size of the system plays an important role: although tendentially more fragile, large systems are able to redistribute and absorb the effects of damage even with low complexity. The theoretical considerations are applied to a real case: a statically indeterminate truss structure is presented and randomly damaged. The results are discussed and the possibility of using the normalized structural complexity index as a potential metrics for testing the efficacy of alternate load path strategy in structural design is critically debated.