EXTREME VALUE ANALYSIS AND JOINT DENSITY OF METOCEAN LOADS FOR MALAYSIAN WATER

Abstract

Environmental load is the main key to designing the coastal structure which consist of wind speed, wave height and wave current. These environmental loads strongly affect all kinds of maritime activities especially the platform stability, and their worst effect is typically caused by the maximum wave height. In order to avoid the platform subjected by extreme loadings, the design crest elevation should be above the extreme flood level, which is usually composed of tides and storm surges along with tsunami, el Nino, and other climate and geological effects. The extreme wave height may be determined with the annual maxima or joint density distribution. Platforms are usually designed based on the parameter of 100-year return period. The 100-year return period is for the wind speed design, wave height design and also for the current design. The data is collected either by in-situ measurement or by Hindcast analysis which has been practiced by the operation for better research and findings. For this research, the Gumbel distribution is used to forecast the 100-year event, while the correlation of joint density and environmental loads is achieved by Weibull distribution. These methods are applied in order to provide the correlation of wind and wave as well as wave and current. In addition, the benchmark can be set up for the operational region of the operation. The interim guidelines will be useful to expect the joint densities in this region and it will benefit the operation on optimization the current design cost and time completion with lighter platform design. Based on the study conducted, it is proposed that for a wave load mean return interval (MRI) is 100 years while for wind load design and the current load design is 10 years for 6 platforms which are the study parameter.