RELIABILITY ANALYSIS OF 3-LEGGED AND 4-LEGGED OFFSHORE FIXED PLATFORM WITH STATIC PUSHOVER LOAD BY WSD AND LRFD METHOD

• Main Author: PRAMITYA WINARNO (nim : 25515302), TIA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/31297
• Institution: Institut Teknologi Bandung

<p align="justify"> Offshore platform is a structure located in offshore which used for extracting, processing, and storage of oil and gas products. Offshore platform was divided based on the function which are drilling platform, production platform, accomodation platform and flare platform. Planning the structural design of offshore platform referring tp API RP 2A standard. There are two design methods in API RP 2A, namely API 2A WSD and API 2A LRFD. Design standard of API 2A WSD utilizes the method of loading working stress design. Whereas for API 2A LRFD utilizes the environmental load factor based on the randomness from environment of Gulf of Mexico. Based on API 2A LRFD method, there is possibility of mismatch with Indonesian waters. Structural analysis includes in-place, seismic, fatigue and pushover analysis were performed on the 3-legged and 4-legged offshore platform which has been established in the Java Sea using API RP 2A WSD and API 2A LRFD methods. This analysis obtains unity check value on main members to get to know optimization of structure by replacing those main members so that the 3- legged and 4-legged structur will be optimized as per API 2A WSD and API 2A LRFD. While based on static pushover analysis, the reserve strength ratio (RSR) value for 3-legged and 4-legged obtrained using variation of 20 waves variations. Reliability analysis with First Order Reliability Method II (FORMII) approach of random wave load variable, performance function using function of Reserve Strength Ratio (RSR) value with 20 wave variations. From the RSR’S value, it is known that those two fixed offshore platforms have minimum RSR value in the direction of 120 degree for 3-legged and 0 degree for 4-legged. In accordance with the calculation of reliability index value (&#946;) from those fixed offshore platforms, the results of reliability index value (&#946;) obtained are 3.09 for 3-legged WSD, 3.13 for 3-legged LRFD and 2 for 4-legged WSD, 2.5 for 4-legged LRFD. It can be concluded that the reliability index value (&#946;) with API RP 2A method is greater than the reliability index value (&#946;) API RP 2A WSD method. <p align="justify">