Environmental Load Factor Calibration for Three-Legged Flare Jacket Platform in Madura Strait With Reliability Analysis Method
Axel 1 dan Prof. Ricky Lukman Tawekal, Ph.D. 2
Program Studi Magister Teknik Kelautan
Fakultas Teknik Sipil dan Lingkungan, Institut Teknologi Bandung
Jalan Ganesha 10 Bandung 40312
axel.ng8898@gmail.com 1 dan ricky@ocean.itb.ac.id 2
Abstract
There are several standard codes that are commonly used in designing fixed offshore platforms, such as API RP 2A-WSD which uses the WSD method, and ISO 19902 which uses the LRFD
method. The LRFD method uses different factors for the member capacity and the load received by the structure so that it will produce more uniform reliability. In the ISO 19902 code, the suggested environmental load factor is 1.35, which is the result of calibration in the Gulf of Mexico, which has different characteristics from the Indonesian waters. In this research, environmental load factor calibration will be carried out for the three-leg jacket flare structure in the Madura Strait. The structure is designed to be optimized for in-place only for calibration purposes. Wave height, current velocity, yield strength, modulus of elasticity, and correction factor are considered as random variable. Sensitivity analysis shows that wind speed has insignificant effect on UC, so it is considered deterministic. Then load modeling is carried out using a stress as a function of wave height and current velocity. Furthermore, reliability analysis was carried out with FORM II and the results were compared with the results from Monte Carlo Simulation. From the reliability analysis, the reliability index for the API RP 2A-WSD design (UC 0.99) is 3.49. The environmental load factor calibration is carried out with the reliability of the API RP 2A-WSD structure as the reliability target. The API RP 2A-WSD design was chosen because the design code has long been used in Indonesia and has proven to be capable. Thus, the environmental load factor so that the reliability of the ISO 19902 design equivalent to API RP 2A-WSD is 1.23.
Keywords: reliability, jacket structure, environmental load factor, FORM II
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