MEASURES OF STRUCTURAL ROBUSTNESS: SYSTEM INTEGRITY AND COMPARTMENTALIZATION

The current code approaches for engineered systems are generally conceived on the basis of component designed philosophy, where explicit requirements are mostly specified at component level or at individual members. There is very little guidance on the overall safety and the approach for design to prevent progressive collapse as a result of abnormal loading is not standard. Several reference papers on the subject treat the problem qualitatively. Following a recent scheme in the literature, in which structural integrity is captured in the structural stiffness matrix, in this presentation we will treat the problem through a quantitative approach extending the analysis from the linear elastic case to the plastic deformation range in terms of frames removal or plastic hinges insertion. With this aim we discuss system integrity measures, and we suggest that the inverse of the stiffness matrix condition number (the so called metric distance) gives a better representation of structural integrity. We also discuss the compartmentalization problem and introduce for the first time quantitative measures of it. We finally apply such new measures to simple examples and show an optimization problem related to the structural integrity.