ABSTRACT
The continued use of the huge stock of existing buildings, that makes the everyday life possible in a country like Italy, requires that not only continuum research efforts are made to set up reliable and specific methodologies and technologies to conduct controls and investigations regarding their structural efficiency and to execute adequate maintenance plans and, when necessary, repair and strengthening interventions, but also indispensable adjustments of the principles of the structural safety and of the ways how it is quantified. Clear traces of what above can be found in the recent updating of the Italian national structural codes where particular importance is assumed by some innovations regarding structural safety issues. The very critical issue is that the general recognized context of limited resources really available to make systematic interventions aimed to improve the structural safety of existing structures obliges to find a right balance between “structural safety” and “sustainability”, as clearly stated in the very important international standard ISO 13822 Bases for design of Structures – Assessment of existing structures. In this respect, major results are obtained on one side limiting as much as possible the effects of “overdesign” of structural interventions that can be connected to the use of consolidated, necessarily “simplified”; procedures in use for verifying the structural safety of new structures and, on the other side, maximizing the effects, measured in terms of “risks reductions”, connected to the use of the effectively available resources to execute repair and strengthening interventions. From the designer’s operative point of view a particular importance is assumed in this context by the so called “knowledge phase”, i.e. a deep, reliable knowledge of which are the real capacities of an existing structure to resist any type of possible action.
