UNCERTAINTY PARAMETERS OF THE MEASURED AND CALCULATED WAVE FORCES ON THE PERFORATED CAISSON BREAKWATER

Abstract

The purpose of this study is to analyze the uncertainty of the wave forces on the perforated caisson breakwater. Understanding the uncertainty of the wave force enables the caisson breakwater to be designed reasonably and economically. Theprobabilistic design methods, such as the reliability-based design method or the performance-based design method that are based on the reliability principles of ISO 2394 and ISO 21650, are becoming a global design standard. In this study, the uncertainty parameters of perforated caisson breakwaters were evaluated by using the normal and the log-normal distributions. The representative parameters evaluating the uncertainty of the wave forces are the bias and the coefficient of variation for the normal distribution and the scale and location parameters for the log-normal distribution. For the narrow chamber case (Group 1), most of the wave forces followed the normal distribution except for the wave force acting on the slit part at the crest I. The bias in Group 1 was widely distributed from -39 % to 79 % depending on the wave phase and the wave force. For the wide chamber case (Group 2), all the wave forces followed the log-normal distribution, but the uncertainty parameters of the log-normal distribution cannot directly be applied in the design process. The bias in Group 2 was also widely distributed between -55 % and 14 %.robabilistic design methods, such as the reliability-based design method or the performance-based design method that are based on the reliability principles of ISO 2394 and ISO 21650, are becoming a global design standard. In this study, the uncertainty parameters of perforated caisson breakwaters were evaluated by using the normal and the log-normal distributions. The representative parameters evaluating the uncertainty of the wave forces are the bias and the coefficient of variation for the normal distribution and the scale and location parameters for the log-normal distribution. For the narrow chamber case (Group 1), most of the wave forces followed the normal distribution except for the wave force acting on the slit part at the crest I. The bias in Group 1 was widely distributed from -39 % to 79 % depending on the wave phase and the wave force. For the wide chamber case (Group 2), all the wave forces followed the log-normal distribution, but the uncertainty parameters of the log-normal distribution cannot directly be applied in the design process. The bias in Group 2 was also widely distributed between -55 % and 14 %.