Performance-based design of concrete structures: durability aspects

In the context of performance-based design (PBD), sustainability considerations and whole life costing, time is the critical variable and durability issues are pronounced. These facts have gained considerable attention during recent years, which is reflected also in standardization activities, e.g.: ISO 13823 (2008) and the newly prepared fib-Model Code (see fib Bulletin 2006). Both these documents are based on probabilistic approaches and enhance the design/assessment of structures for durability. In a practical sense, for concrete structures considered from the standpoint of durability, PBD means identifying and calculating as design parameters e.g. the service life, concrete cover, quality of concrete and the relevant reliability index value in the context of the appropriate Limit State (LS). This should be done in conjunction with balancing or optimizing the long-term economic consequences, technological feasibility, planning of inspections, maintenance and other factors. Such complex decision making needs special methodology, software tools, an experienced designer and his/her close cooperation with the client.