On the Use of Directional Wave Criteria

Abstract

Directional wave statistics can be used to optimize the design of offshore structures which are not symmetrical. Unfortunately there does not appear to be any consensus on how directional design criteria should be developed or used. Using simple examples, we show that commonly used methods are unconservative. In order to preserve the reliability given by designing to omnidirectional criteria, the product of the probabilities of nonexceedance from all of the direction bands must equal the omnidirectional probability. We suggest a simple method for assuring consistency between omnidirectional and directional criteria.