ASSESSING THE COST OF SUBJECTIVITY IN REINFORCED CONCRETE BRIDGE INSPECTIONS

Numerous reinforced concrete (RC) bridges worldwide have surpassed their design serviceability life and habitually incorporate potentially severe defects. To ensure the ability of a bridge to carry on with its designed duties and the safety of its users, a series of inspections, monitoring and maintenance protocols should be regularly carried out. The most common inspection approach is the visual assessment of structural defects performed by trained engineers. Commonly, the output of such inspections is a grade indicative of the gravity of the defect i.e., an In-Situ Defect Grade (ISDG). On the grounds of the latter, one can formulate simplified risk evaluations and prioritize the maintenance interventions. A key problematic related to directly assigning an ISDG is its inherent subjectivity as it strongly depends on the inspector’s safety condition assessment expertise and background. The present article intends to analyze and quantify the above issue. In particular, the authors introduce a novel algorithm that assesses the bridge condition objectively and univocally in the form of a grade. This, by means of a novel class-based evaluation expressly designed to extricate the complex meaning of defect evaluation, thus reducing the subjectivity of the grade. Given a database of the defects of a set of bridges evaluated in-situ, the algorithm sets the newly introduced grades against the ISDGs by means of a confusion matrix. The purpose, studying their proximity and spotting any correlation. On the basis of the goodness of the correlation, the authors explain how to evaluate the cost of subjectivity-induced inspection errors for a broad variety of inspection practices.