Mathematical formulation using experimental study of hydrodynamic forces acting on substructures of coastal pile foundation bridges during earthquakes: As a model of human bridge protective

Abstract

The substructures of sea-crossing pile foundation bridges, which are located in zones with active seismicity, are vulnerable to earthquakes and water forces that induce damage during their beneficial operation. This study investigated the behavior of this type of bridge under the combined influence of water forces represented by currents and waves during seismic actions. This study proposed a method for analyzing Morison equation and simplified its inertial and drag coefficients. A new technique called the reality water-structure-earthquake interaction test (RWSEIT) has been developed to study the hydrodynamic pressure distribution and acceleration along the height of the pile foundation of a 1:20 scale concrete model. To find Morison coefficient values, the changing rule of hydrodynamic pressure with water depths, current speed, wave properties, earthquake amplitudes, and earthquake frequencies is studied. The results proved that the inertial coefficient has the same changing rule as the drag coefficient. The inertial coefficient ranged from 0.117 to 1.950 and the drag coefficient ranged from 0.017 to 0.230 under various studied conditions. Finally, a statistical analysis was carried out based on the results from the tests, and two equations for the inertial and drag coefficients were introduced, with correlation coefficients of 0.9 and 0.92, respectively.