Structural Vulnerability of Coastal Bridges under a Variety of Hydrodynamic Conditions

Coastal bridges are prone to failure during extreme hurricane events. Engineers can prevent failures of coastal bridges during extreme hurricanes by ensuring that wave forces do not exceed the structural capacity of the bridges. To understand the performance of bridges in coastal areas during hurricanes, empirical equations have been applied to several bridge decks in Louisiana by assuming different hydrodynamic conditions. Several plots were created to illustrate and compare the uplift and horizontal forces on bridge decks provided by these three sets of equations. The analysis demonstrated that the maximum vertical force during a hurricane event could potentially cause uplift of the superstructure. The equations predict that when the superstructure is partially or fully submerged, the uplift forces can exceed seven times the weight of the superstructures and the horizontal forces could reach up to 35% of the weight of the superstructures. Further work is required to determine the accuracy of these equations when the water level is higher than the lower chord of the girders of the superstructure.