Condition assessment for bridges: a hierarchical evidential reasoning (HER) framework

Abstract

Infrastructure risk management practices enable decision-makers to effectively monitor and assess structural condition for repairing/replacing elements before major damage or collapse state is reached. Improved techniques have enhanced inspection and monitoring of infrastructure, but assessment and interpretation of the collected data remains a challenge. In this article, a hierarchical evidential reasoning (HER) framework is proposed for the condition assessment of bridges. The approach involves using a HER framework for classifying bridge data into primary, secondary, tertiary and life safety-critical elements. The proposed HER framework combines different distress indicators (bodies of evidence) at different hierarchical levels. The information is aggregated using Dempster–Shafer (D–S) and Yager rule of combination to propagate both aleatory and epistemic uncertainties throughout the model. Furthermore, importance and reliability factors (collectively termed ‘‘credibility factor’) are introduced for discounting evidence based on importance of bridge element and reliability of the collected data. The data are systematically combined to obtain primary/secondary/tertiary/life safety-critical condition indices. Finally, an overall bridge condition index is obtained. The indices are based on information from multiple sources thereby providing a more reliable assessment of bridge condition. The HER framework is applied to data from an existing bridge in order to demonstrate application of the proposed approach.

Keywords:

• evidential reasoning
• Dempster–Shafer (D–S) theory
• condition assessment
• bridge management
• credibility factors; infrastructure; decision-making; uncertainty modeling; risk management

Acknowledgements

The financial support from Natural Sciences and Engineering Research Council of Canada (NSERC) under Discovery Grant Program is acknowledged.