Abstract
Practical applications in ocean engineering require the long-term analysis for prediction of extreme waves, that identify design conditions. If extreme individual waves are investigated, we need to combine long-term statistical analysis of ocean waves with short-term statistics. The former considers the distribution of standard deviation of free surface displacement in the considered location in a long-time span, of order of 10 years or more. The latter analyzes the distribution of individual wave heights in a sea state, which is a Gaussian process in time domain. Recent advanced approaches enable the combination of the two analyses. In the paper the analytical solution is obtained for the return period of a sea storm with at least two individual waves higher than a fixed level. This solution is based on the application of the Equivalent Triangular Storm model for the representation of actual storms. One of the corollaries of the solution gives the exact expression for the probability that at least two waves higher than fixed level are produced during the lifetime of a structure. The previous solution of return period and the relative probability of exceedance may be effectively applied for the risk analysis of ocean structures.
Highlights
The concept of Equivalent Triangular Storm (ETS) was introduced by Boccotti in the eighties [1, 2]
A complete analysis was given in Boccotti [3], where the ETS model was applied for solving in a closed form of some long-term problems, which are very useful for the design of coastal and offshore structures
The ETS model represents each actual storm as a triangle, where the triangle height is equal to the maximum significant wave height during the actual storm and the triangle base is such that the maximum expected wave height in the actual storm is equal to the maximum expected wave height in the triangular storm
Summary
Return Period of a Sea Storm with at Least Two Waves Higher than a Fixed Threshold. Natural Ocean Engineering Laboratory, Department DICEAM, “Mediterranea” University, 89122 Reggio Calabria, Italy. If extreme individual waves are investigated, we need to combine long-term statistical analysis of ocean waves with short-term statistics. The former considers the distribution of standard deviation of free surface displacement in the considered location in a long-time span, of order of 10 years or more. In the paper the analytical solution is obtained for the return period of a sea storm with at least two individual waves higher than a fixed level. This solution is based on the application of the Equivalent Triangular Storm model for the representation of actual storms. The previous solution of return period and the relative probability of exceedance may be effectively applied for the risk analysis of ocean structures
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