Response of the offshore jacket platform at its ultimate strength under operating and extreme loads: a Malaysian waters case study

Abstract

ABSTRACT Before reassessing the reliability condition of an offshore jacket platform, it is essential to understand the behaviours that the offshore platform exhibits while it is at sea. This paper presents the response of the offshore jacket platform as its ultimate strength under operating and extreme loads. Malaysian waters’ metocean data from a 1-year return period (operating condition) and a 100-year return period (storm condition) are used to predict the four-legs jacket platform's behaviour by evaluating its ultimate strength. Also, two values of minimum design water depth (WD) of 105.9 m and maximum design WD of 115.4 m are chosen. The SACS software, a nonlinear finite element analysis software, is used to calculate the jacket platform's ultimate strength, called pushover analysis. For instance, the pushover analysis result will determine the Reserve Strength Ratio (RSR) as an approach to examining the offshore jacket platform's ultimate strength. Responses to the offshore jacket platform are base shear design, base shear ultimate, rotation, displacement, and moment, which illustrate the behaviour of the offshore jacket platform. There are eight combinations of environmental load directions are applied, to obtain the structure's weakest part. It is found that 45° is the critical direction for maximum design WD, while 90° is the critical direction for minimum design WD. The study's findings indicate that the response of the offshore jacket platform is very important for the safe design and operation of offshore jacket platforms.