Seismic risk-informed prioritisation of multi-span RC girder bridges considering knowledge-based uncertainty

In earthquake-prone countries, transport network managers need to perform extensive seismic risk assessments coping with a considerable number of bridges characterised by an unsatisfying knowledge level and designed in the past without anti-seismic requirements. This study proposes a framework for efficient risk assessment of multi-span girder bridges considering knowledge-based uncertainties. The framework is intended to be applied to risk-informed prioritisation of bridge portfolios. It is based on subsequent modules that involve the input of knowledge data, the simulation of knowledge-based uncertainties, simplified seismic analysis, fragility and loss assessment. The seismic vulnerability of a given bridge is represented by loss ratio percentiles related to a given seismic intensity measure which can be used to quantify the expected annual losses and the corresponding variability due to the influence of knowledge-based uncertainty. A case-study section demonstrates the framework for the widespread category of simply supported girder-reinforced concrete bridges. It addresses issues such as the use of optimal intensity measures, the required number of model realisations and discrepancies with respect to accurate nonlinear time-history analysis. Finally, an illustrative example of the proposed framework for eight case-study bridges in Southern Italy demonstrates its applicability for seismic risk-informed prioritisation of critical bridges and for directing in-depth knowledge data collections where needed.