ABSTRACT
The change in climate causes global warming and induces adverse impacts on riverine flood patterns by making intense flood events in future. This will result in higher scour depths at foundations of river-crossing bridges located in climate change-sensitive regions. Bridge scour beyond a certain limit may alter dynamic characteristics of bridges making bridges scour-critical. Scour-critical bridges are not safe and should be closed from traffic until appropriate scour countermeasures are undertaken. The situation would be more critical if an earthquake strikes to a bridge having scour at foundations. Such a scenario (i.e., earthquakes in the presence of flood-induced scour) is considered to be a multihazard condition for bridges. Past studies demonstrated that this multihazard scenario can intensify the vulnerability of bridges located in seismically-active flood-prone regions. Coupled with climate change, this multihazard has even higher potential to paralyze bridge systems and produce severe consequences in future. With an objective of evaluating the impact of climate change on multihazard vulnerability of bridges, the study here analyzes a river-crossing existing bridge in California. Changing characteristics of the design flood (i.e., 100-year flood) at the bridge site is assessed for a projection period, 2012 – 2099. This projection is done based on observed annual peak discharges of the river at the same site from 1930 to 2011. Projected data is used to generate flood hazard curves of the region for two non-overlapping periods, 2012 – 2050 and 2051 – 2099. These curves show increased flow discharge of 100-year flood events as time elapses. Research outcome, expressed in the form of fragility curves, exhibited vulnerability of the bridge elevated under the stated multihazard condition from observed to projected periods; this impact is solely due to anticipated change in climatic condition of the study region.
