Multi-state functionality restoration of highway bridges using stochastic process

Abstract

Rapid restoration of highway bridges under disruptive events is essential due to the significant socio-economic consequences resulting from bridge closure. Functional bridges enable the community’s immediate response, other lifeline systems' recovery, and network accessibility. This study proposes a risk-based approach for the resilience assessment of bridge systems using the state-dependent restoration process. The semi-Markov process (SMP) is employed to model functionality restoration and subsequently bridge resilience. To this end, bridge resilience has been quantified as a measure of multi-state functionality restoration with respect to time. Unlike traditional performance-based earthquake engineering (PBEE), the proposed framework enables the functionality restoration of a system to be characterized as a state-dependent process. The Monte Carlo approach is used to simulate functionality restoration curves considering uncertainty associated with hazard intensity and corresponding state durations, or repair times. This paper evaluates the scenario-based resilience of the bridge under concurrent effects of earthquake and flood-induced scour hazards. In so doing, multi-state functionality and resilience for bridge cases with different scour depths (ys= 3 m and 6 m) are estimated using the SMP and PBEE approaches. The simulation-based results were then compared with the benchmark case without scour. Based on the multi-hazard resilience assessment, lower values of resilience index are obtained from scoured bridge cases compared to zero-scour condition. Finally, the results from the SMP are compared with the PBEE for a two-state bridge system. The proposed state-dependent stochastic framework can provide decision-makers with information to quantitatively assess and enhance bridge resilience in an integrated manner.