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The damage acting on a structure can lead to disproportionate consequences, i.e., the global collapse. This extreme situation has to be avoided and, thus, structural monitoring is requested in those structures where human losses are possible and large economic consequences are expected. Static measurement devices are the most economic instrumental set-ups able to highlight the presence of progressive damages. However, this monitoring system suffers from the structural behaviour under the external loads. In many situations, alternate load paths shown the non-effectiveness of the measurement system since the instrumentation are installed on elements not relevant for the response under the given loads. The same problems occur when the structure is compartmentalized, i.e. the structural responses of the single parts dependent on the loads acting almost only on the same single component. In order to measure the degree of compartmentalization, different novel metrics based on stiffness matrix properties are proposed and their effectiveness discussed. The new idea of this paper is to connect compartmentalization of structures with a sort of distance of the stiffness matrix from the set of diagonal matrices. Few examples are illustrated

Different procedures for assessing the robustness of a reinforced concrete (RC) frame under progressive damage are proposed and compared. The removal of a column in a RC frame structure is modeled with a commercial nonlinear finite element software according to three alternative strategies: (i) reduction of mechanical properties of the damaged column, (ii) incre- mental loading of the structure after total removal of the damaged column, and (iii) incremental unloading of internal forces on the damaged column. Nonlinear analysis is performed under a prescribed load combination on three concrete frames designed with three Italian building codes in force in different periods. Despite the differences in the strategies for damage mod- eling, similarities between structural response predictions are highlighted. In addition, it is shown that seismic design provisions for RC building structures increase the ductility of the structure but do not guarantee the robustness against the removal of a column.