Experimental evaluation of shape effects on elevated structures subject to waves

Elevated coastal infrastructure, including coastal bridges and free surface breakwaters, is increasingly subjected to unexpected wave forces due to intensifying storm surges and rising sea levels. Despite the importance of structural geometry in wave–structure interaction, limited previous studies have examined how different cross-sectional shapes influence wave loading under these extreme sea conditions. This study addresses this knowledge gap via a series of one-to-ten scale experimental studies. Three representative parameters are selected: cross-sectional shapes (a “discontinuous” shape representing a common box-girder shape, and two “continuous” shapes – concave and convex), wave scenarios (regular and irregular waves), and structural elevation relative to still water level (semi-submerged, at SWL, and elevated above SWL). Subsequently, wave transmission, wave reflection, and wave forces imposed on the structure are evaluated based on the results. Overall, among the shapes tested, the convex shape demonstrates the most favorable performance in reducing horizontal forces, while the concave was most effective in minimizing uplift forces. Additionally, the results identify alternative shapes suitable for implementation such as protective facades in retrofit applications or as primary structural forms in new construction which offer significant potential for impulsive force reduction.