Calculation method of hydrodynamic force on one column of the twin columns under earthquake

Abstract The calculation method of the hydrodynamic force on twin-column pier receives less concerns although this kind of pier has been widely used in real practice. The three-dimensional twin-column deep-water pier is simplified as a two-dimensional twin-column model and water is assumed to be irrotational, inviscid and incompressible. The analytical solution of hydrodynamic force on twin columns is deduced, and the calculation equations of the hydrodynamic forces on one column of the twin columns are founded based on the calculation equations of single column by introducing the added mass modified coefficients h x and h y . Commercial software ANSYS FLUENT is employed to validate the analytical solution. Comparison between the analytical and numerical methods show the analytical solution agree well with the numerical solution. The influences of variables, i.e. Reynolds number, Keulegan-Carpenter number, polar angle, and relative center distance, are discussed analytically and numerically, as well as the generating mechanism of the lift force. A case study of hydrodynamic force on a real bridge under earthquake shows the proposed calculation solution is not only concise in expression form, but also with good precision and high calculation efficiency, which exhibits a high application value in real practice.