Extensive research and studies have been carried out to determine the durability of concrete under various service conditions, and thus information on the pro­gressive changes in the physical and chemical nature of concrete under such conditions is available through technical committees and publications of organizations such as the ACI, International Union of Laboratories and Experts in Construction Materi­als, Systems and Structures (RILEM), and Interna­tional Federation for Structural Concrete (CEB-FIP). Available damage models for reinforced concrete in large measure have addressed corrosion of steel reinforcement in concrete and new construction. Improved damage models and guidelines for their use are desired to predict failure probability of a degraded concrete structure, either at present or at some future point in time. Additional investigations also are desired with respect to synergistic effects involving more than one degradation factor and the interaction of loading and environment.