A METHOD FOR DETERMINING LIMIT STATE DESIGN WAVE USING PERIOD DISTRIBUTION FUNCTION

摘要

All waves acting on a breakwater during its design lifetime (for example, 50 years), represented by their frequency of occurrences according to wave scale, are defined as the fatigue limit state design waves. In Japan, wave heights with a frequency of occurrence equal to 10~4 are adopted as the serviceability limit state design wave for the purpose of controlling cracks in concrete structure. For determining the limit state design wave for the purpose of designing port structure components, the method proposed by Nagao (1994) employs the average wave period equivalent to 1/1.2 times the significant wave period without considering frequency distributions, although the method takes account of wave height frequency distributions. From analysis of individual waves contained in raw wave data obtained at the ports of Shimoda and Omaezaki, both located on the Pacific coast of Japan, the authors have verified that the period of large individual waves with a height of 2m or more which is of significance for design purposes corresponds to a significant wave period. Since wave force varies with wave period, it is important to determine an appropriate period for the limit state design wave.