The irregular wave force on pier group

In this paper, the irregular wave force on a cylindrical pier group is calculated by the method of spectrum analysis, and the coefficients of the group effect of piers in the pier group are given here.The calculated results, using P-M and Bretshneider's. (B's) spectra, are obtained for the cases of 2 piers, 3 piers and 4 piers.To compare these results with those obtained for regular waves, we can come to some significant conclusions.Under the action of the irregular wave, when the distance between the piers in the pier group increases, the coefficient of the group effect decreases and tends rapidly to the case of a single pier.In general, when the ratio of the distance between the piers to the diameter of the pier is greater than 4, the group effect can be neglected.