An SPH study of cross-sectional shape effects on coastal structures subject to regular wave forces

Wave loads induced by extreme events are devastating to coastal communities with vulnerable infrastructure. Structures such as breakwaters and coastal bridges, should be properly designed to withstand wave loads. Cross-sectional shapes are important in wave-structure interaction but there is a lack of systematic comparison between different shapes on their wave forces. This paper presents a study on how structural shape modifications can lead to reduction of wave forces. Various cross sections are considered, including a discontinuous shape that has an overhang that forms a corner discontinuity (such as the common box girder bridge), and continuous shapes that have a smooth geometric transition. Continuous shapes include both concave and convex sides. Different regular wave scenarios are created with different wave characteristics and relative structural elevation. Smoothed particle hydrodynamics (SPH) is employed and a 1:10 scaled laboratory experiment was first conducted to validate the numerical scheme of SPH. The numerical study shows that continuous shapes can reduce wave forces by more than 50 % in some scenarios compared to the discontinuous shapes, because continuous shapes have smooth geometric transitions to avoid abrupt change in the flow velocity of waves, thus eliminating impact forces that occur on the side-overhang intersection of discontinuous shapes. The results show the importance of shape modification on reducing wave forces, which can lead to both new construction and retrofit insights that enhance coastal resilience.