Combining multirisk regional assessment of civil infrastructures with material degradation. A brief review

Civil infrastructures are naturally subjected to multifaceted risks derived from internal or external causes, natural or human-made. This brief discussion investigates the effect of exogenous and endogenous threats on the structural integrity of bridges and viaducts in Mediterranean areas at the network level. In this region, the most likely risk sources derive from earthquakes and hydrogeological effects. The immediate and catastrophic damage induced by such exogenous threats is often combined with endogenous risks, involving intrinsic factors, such as material degradation, design flaws, and construction deficiencies. Again, these pose significant challenges to the longevity of bridge structures on their own; yet, they also facilitate structural failures triggered by seismic or extreme weather event. Nevertheless, the current scientific literature lacks established methodologies for jointly assessing seismic and hydrogeological risks considering also degradation and wearing of road infrastructures. The discussion provided herein emphasizes the need for holistic, comprehensive risk assessment and proactive maintenance strategies to mitigate these threats and ensure the resilience and structural safety of civil infrastructures, also propagating the risk at the regional level.