In this paper a framework for assessing the robustness of existing reinforced concrete structures under corrosion is presented. Robustness is defined as a structural property related to the tolerance to damage and is measured by ithe mean performance considering all possible damage scenarios. The proposed methodology is driven to meet the requirements of the structural maintenance interventions in the real lite, as it can be used to define the structural types with longer lifecycles (including both deterioration and loading) or, alternatively, those which may present longer time interval between maintenance/strengthening operations. This is an important issue when dealing with the life-cycle management of existing deteriorated structures. In fact, when facing limited funding for the management of a large stock of bridges, the crucial question is whether postponing a specific repair/strengthening work increases the repair cost disproportionately. Firstly, a robustness index based on the deterioration process is proposed and explained. Secondly, the application to two real bridges shows how this index may help to solve the question and to see which bridges are more sensitive to a postponing of the maintenance works, based on a life-cycle approach.