Statistical Modelling of Environmental Load Uncertainty for Jacket Platforms in Malaysia

Proper evaluation of load is the most important step
for the design of a structure. This paper presents the uncertainty
modeling of environmental load for jacket platforms in Malaysia.
We are interested only in extreme loads for the modeling of
environmental load which are distributed by extreme values.
Here in this paper, Weibull or Gumbel distributions are used.
The existing platforms are designed for 100 year return period
but are assessed for 10,000 years as recommended by ISO 19902
and API RP2A. The nature of environmental load is
probabilistic and we need to ascertain the randomness of the
load. This study covers three parameters of environmental load
acting on jacket platforms namely significant wave height (Hs),
wind speed and surface current speed in the Peninsular Malaysia
(PM) region. Two-parameter Weibull and Gumbel distributions
were used for the analysis. The data is in shape of 1, 10, 50, 100
year return period. Parameters of distribution are determined
first, which are used to find mean and standard deviation of
respective distribution. From this, uncertainty variables are
extrapolated up to 1000 and 10,000 years. Finally the data was
compared with data from Gulf of Mexico (GOM), Northern
North Sea (NNS), Southern North Sea (SNS) and Central North
Sea (CNS). This work will lead to determining the reliability of
jacket platforms in Malaysia.