Multi-hierarchical durability assessment of existing reinforced-concrete structures

Durability of an existing reinforced concrete structure is one of the most important problems for its users and owners. However, no systematic durability assessment approach exists currently. The assessment results vary in relation to the knowledge, expertise, and partiality of the assessor. Additionally, most assessment may not focus on all the key system parameters that affect structural durability. This paper aims at establishing a systematic durability assessment approach for R.C. Structures. The development of such an approach would help to identify all major parameters that affect structural durability and in addition, would enable assessors to collect both qualitative as well as quantitative information in a standard format for any given reinforced concrete structure. Furthermore, such a systematic assessment approach would provide a fair and objective way for analyzing and dealing with data collected by field inspection. Firstly, by Saaty's ratio scaling method, which scientifically quantifies the subjective information of expert judgments. Secondly, on basis of the properties of entropy, which combines the subjective information of expert judgments with the intrinsic information of assessment parameters. Then, taking gray relation grade as criterion, which obtains the deterioration degree and deterioration rate for a given structure. Finally, based on the assumption that deterioration varies with time exponentially, it gives the present performance and residual service life for any existing reinforced concrete structure.