ABSTRACT
Civil infrastructure systems can be heavily affected by outages and disruptions of critical facilities. In particular, road infrastructure networks play an important role in the emergency response to seismic events and related hazards, to ensure both a quick deployment of aids and resources to distressed communities and a prompt repair of the surrounding lifelines and buildings. Bridges are the most vulnerable components of road networks and the assessment of their structural performance and functionality and the definition of effective post-event recovery processes are hence key factors to ensure suitable resilience levels of the entire network.
Resilience of structure and infrastructure systems is generally investigated considering damage and disruption caused by sudden extreme events, such as earthquakes (Bruneau et al. 2003, Chang & Shinozuka 2004, Bruneau & Reinhorn 2007, Bocchini & Frangopol 2011, Decò et al. 2013, Titi et al. 2014, Biondini et al. 2015b). However, damage could also arise continuously in time due to aging and structural deterioration, which can modify over time the structural performance and functionality and, consequently, the system resilience. Therefore, for structures and infrastructure facilities exposed to seismic and environmental hazards, resilience depends on the time of occurrence of the seismic event (Titi & Biondini 2013, Biondini et al. 2015a).
This paper presents a probabilistic approach to seismic assessment of aging bridge structures and resilience analysis of highway road networks. The emphasis is on reinforced concrete bridges exposed to chloride-induced corrosion. The time-variant seismic capacity associated with several limit states, from damage limitation up to collapse, is assessed for deteriorating bridges in the network. The level of seismic damage is related to vehicle restrictions and traffic limitations and a traffic analysis is carried out over the entire road network to compute the system functionality and the corresponding seismic resilience under prescribed post-event recovery scenarios. The proposed approach is applied to a four-span reinforced concrete bridge under corrosion considering different types of highway networks with detours and re-entry links. The results show that the seismic resilience of highway networks decreases over time due to structural deterioration of bridge structures.
