DETERMINATION OF ENVIRONMENTAL LOAD FACTOR OF JAVA SEA FOR BRACED MONOPOD USING RELIABILITY ANALYSIS METHOD

• Main Author: Epafras Hadi Saputro, Erick
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/46826
• Institution: Institut Teknologi Bandung

Analysis of offshore structures follows the criteria set by API RP-2A with the LRFD and WSD design methods. The basis of this method is the environmental conditions in the Gulf of Mexico which are actually more extreme than Indonesia’s sea. The structure designed by this method applied in Indonesia is very safe. This resulted in the cost of creating the structure becomes more expensive. The wave standard used requires 100 years of waves. Therefore, research needs to be conducted to provide recommendations on the value of environmental burden factors in Indonesian waters that are quieter than those in the Gulf of Mexico. In this study, an analysis of the braced monopod structure is placed in the Java Sea by using a base shear as a guide to describe the strength of the structure and the working load. The load used is the annual H max 100 wave load at vertical loads of 1000kN and 500kN. The author conducts a pushover / collapse analysis to produce structural strength parameters based on the value of the reserve strength ratio (RSR) and static inplace analysis to obtain the wave load parameters due to the randomness value of the waves acting on the structure. This analysis was conducted for storm conditions in the Java Sea with the design methods WSD 1.00, LRFD 1.35, LRFD 1.20, LRFD 1.10, LRFD 1.00. Next, a performance equation will be arranged to get the reliability index value (?) with reliability analysis using the FORM II method (first order reliability method). Based on the reliability index analysis (?), the ? value was 5.49 for LRFD 1.35 at 1000kN load and the ? value was 3.17 for LRFD 1.35 at 500kN load. The results of this analysis obtained a wave recommendation to design a braced monopod structure in the Java Sea with a 20-year wave design on the 1.35 LRFD method for 1000kN vertical loads and 500-year design waves on the 1.35 LRFD method for 500kN vertical loads.