Numerical Investigation of Wave Forces on Coastal Bridge Decks

High waves and storm surges create high load forces on the underside of coastal bridge decks due to impact pressure and air compression. Therefore, wave forces need to be comprehensively accounted for at the design stage for coastal bridges. Traditionally, the design of coastal bridges and their capacity to withstand elevated wave forces rely on experimental and theoretical data, but recent improvements in modeling and computer performance have led to the use of numerical analysis, which offers many advantages over experimentation such as faster implementation and cost-effectiveness. However, the accuracy of numerical techniques for predicting the physical effects of wave forces on the decks of coastal bridges still needs to be evaluated. Moreover, existing numerical studies have not included the compressibility of air in calculating the peak wave pressures acting on bridge decks. In this study, three-dimensional fluid analysis was used to reproduce experimental conditions, and the compressibility of air was included in the numerical analyses. Our results confirmed that wave forces can be predicted within the same order of magnitude as experimental values and that the accuracy of numerical results depends on the wave conditions. More importantly, the introduction of air compressibility in the calculations can more accurately reproduce the experimentally observed increase in peak impact pressure and pressure oscillations of waves hitting the underside of bridge decks.