Seismic reliability of reinforced concrete bridges subject to environmental deterioration and strengthened with FRCM composites

Ensuring adequate seismic reliability levels for existing infrastructure components is a key issue for owners in earthquake-prone countries. In particular, bridges may suffer relevant damage in case of a seismic event, and this issue can be magnified due to deterioration phenomena induced by environmental agents, like CO2 emissions or chlorides. Among the available techniques, seismic retrofitting can be pursued through the use of composite materials. For a proper bridge management policy, infrastructure owners need to know at which time instant scheduling restoration interventions on bridges, and such issues have to be fixed with a reliability-based metric. The present study numerically investigates the effectiveness of the use of fabric reinforced cementitious matrix (FRCM) systems in the seismic retrofitting of an existing multi-span simply supported (MSSS) reinforced concrete (RC) bridge subject to aging. Fragility curves are first derived on the basis of refined non-linear time-history analyses performed on the “as built” configuration. Fragilities are further computed for different combinations of deterioration scenarios and seismic retrofitting schemes with increasing number of FRCM layers. Time-variant seismic reliability profiles are thus assessed, and reliability gains achievable at different time instants with the implementation of the FRCM retrofitting scenarios are quantified in order to provide useful information for the infrastructure owner decision-making.