A cause-based defect ranking approach for existing concrete bridges using Analytic Hierarchy Process and fuzzy-TOPSIS

Condition assessment is a crucial step in maintaining and managing existing concrete bridges. Most of the studies consider defects and their severity levels in the evaluation process in the literature. As of now, underlying causes, which play an important role in magnifying existing defects, do not get much attention in the assessment process as per the literature. Thus, this study proposes an integrated Analytic Hierarchy Process (AHP) and fuzzy-Technique for Order of Preference by Similarity to Ideal Solution (fuzzy-TOPSIS) approach to rank defects considering underlying causes. Here, causes and sub-causes are considered as criteria and sub-criteria, respectively. AHP is used to determine relative importance weights of causes and sub-causes. The final defects ranking is obtained using fuzzy-TOSIS. The applicability of the model is demonstrated through a case study on a reinforced concrete bridge deck in Gujarat, India, where 'cracks' is obtained as the most critical defect for this specific case. The robustness of the model is examined by a sensitivity analysis. The proposed approach can help bridge owners to enhance the existing decision-making process of concrete bridges. Moreover, this approach can be considered as a first step into a new way of ranking defects of a more comprehensive system.