Fuzzy Logic Based Condition Rating of Existing Reinforced Concrete Bridges

Fuzzy logic is a means for modeling the uncertainty involved in describing an event/result using natural language. The fuzzy logic approach would be particularly useful for remedying the uncertainties and imprecision in bridge inspectors’ observations. This study explores the possibilities of using fuzzy mathematics for condition assessment and rating of bridges, developing a systematic procedure and formulations for rating existing bridges using fuzzy mathematics. Computer programs developed from formulations presented in this paper are used for evaluating the rating of existing bridges, and the details are presented in the paper. In this approach, the entire bridge has been divided into three major components—deck, superstructure, and substructure—each of which is further subdivided into a number of elements. Using fuzzy mathematics in combination with an eigenvector-based priority setting approach, the resultant rating set for the bridge has been evaluated based on the specified ratings and importance factors for all the elements of the bridge. Then the defuzzified value of the resultant rating fuzzy set becomes the rating value for the bridge as a whole. It is argued that the methodology presented in this paper would help the decision makers/bridge inspectors immensely.