Development of Fuzzy System Dynamics Model to Forecast Bridge Resilience

The occurrence of disasters such as earthquakes, cyclones, tsunamis, and floods affect the resilience of bridges. In the last four decades, about 2,130 bridges were collapsed due to various disasters in India, and out of these, almost 1,105 bridges were ruined due to floods. However, in the existing practice of measuring the resilience of bridges, resilience matrices overlook the dynamism of bridge resilience and fail to address the uncertainty of variables influencing the resilience of bridges due to floods. Therefore, this study aims to develop the fuzzy system dynamics (FSD) model to simulate and forecast bridge resilience considering complex interconnections among different infrastructures and government systems. For this, the study first shortlists 14 variables related to bridge resilience using the Delphi method. Then, the cause-and-effect feedback loop and stock-and-flow diagram are formulated to explore the interdependency among these system dynamics variables of bridge resilience. Fuzzy measures and integral are used to establish the soft relationships and the existing mathematical formulas to explain the hard relationships in the FSD model. The proposed FSD model is used to simulate and forecast scenarios of the resilience of 12 bridges against floods. The structure and behavior of the FSD model are validated by conducting the dimension consistency test, structure verification test, and sensitivity analysis. The proposed model can be helpful to bridge owners to manage bridge assets, prioritize the repair and rehabilitation of bridges, propose the new bridges, devise the new policy, coordinate with other utilities and governance agencies, and thus enhance the bridge's resilience against floods.