STUDY OF LRFD ENVIRONMENTAL LOAD FACTOR DETERMINATION FOR EXTREME ENVIRONMENTAL LOADS IN THE JAVA SEA WITH RELIABILITY METHOD

• Main Author: Jayadilaksana, Fega
• Format: Theses
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/45113
• Institution: Institut Teknologi Bandung

Structural design methods are in the process to shift from the use of WSD to LRFD method, it shows that the uncertainty factor has become an important aspect in the design of a structure. However, the use of the LRFD design method for Indonesian waters is considered inappropriate, this environmental parameter derived based on conditions in the Gulf of Mexico which are more extreme than conditions in Indonesia. Therefore, it is necessary to conduct research to provide recommendations on the value of environmental conditions of extreme conditions (?E = 1.35) for calmer Indonesian waters. This study is based on base shear structure as a guideline to describe the strength of the structure and the magnitude of the load that works. These parameters are obtained from pushover/collapse analysis, which will produce a structural strength parameter (R) based on Reserve Strength Ratio (RSR) value and static in-place analysis to obtain the wave load parameter (S) due to wave random variables acting on the structure. This concept applied to the 4-legs fixed offshore structure located at the Java Sea, the structure has been optimized for the WSD and LRFD design methods to produce a structural optimum design. After the structural strength and wave load parameters are obtained, an equation, a performance function will be processed through reliability analysis using the First Order Reliability Method (FORM) II method to obtain a reliability index (?) structure. The method of reliability analysis in this study was carried out for several values of extreme environmental load factors consisting of ?WSD = 1.00, ?LRFD = 1.35, ?E1 = 1.30, ?E2 = 1.20 and ?E3 = 1.10. Based on the reliability index (?) obtained from the results of the reliability analysis, a recommended value of the extreme condition environmental load factor (?E) with 100-year return period for Java Sea is 1.246.