Research of Calculation Method for Wave Forces Acting on Large-Scale Bridge Piers Based on Diffraction Theory

In order to make the MacCamy diffraction theory applicable to calculate the wave forces on large-scale bridge piers, a calculation method was analytically and numerically investigated. First, the effects of the cross-section dimension and cross-section shape on the bridge pier inertial force coefficients were numerically examined. Then, the diffraction coefficient was introduced into the Morison equation, making the classical Morison applicable to calculate the wave forces on large-scale structures. The results show that the initial force coefficient of the square cross-section pier decreases faster, and the large-scale effects are more obvious in square cross-section piers than in the circular cross-section piers. The analytical solutions obtained from the Morison equation with a diffraction coefficient are very close to the numerical solutions. When the longitudinal wavelength is 0.2 times the wavelength, the wave forces on the large-scale square piers calculated from the modified Morison equation agree well with the numerical results.