Hendriyawan
Currently, there is no standard code in designing earthquake resistance structures for offshore platforms in Indonesia. Most of the platforms in Indonesia using API RP 2A WSD as standard code for designing offshore structures. Two earthquake levels were introduced in the code, i.e. Strength Level Earthquakes (SLE) and Ductility Level Earthquake (DLE). However, this guideline does not explicitly state the return periods and the procedures for developing of those two levels of earthquakes. ISO 19901-2 which has also been adopted and modified in a 2EQ Recommended Practice API (2014) has a clearer procedure in determining the earthquake burden used for seismic analysis of offshore structures. Two levels seismic design were used in ISO guideline, those are Extreme Level Earthquakes (ELE) and Abnormal Level Earthquake (ALE). Two alternative procedures were proposed in ISO 19901-2 for developing those two levels of earthquake, i.e. the simplified method and the detailed method. This paper presents the developing of seismic hazard maps for 1000 years return period for North Java Offshore Indonesia. Two spectral hazard maps for a 1.0s oscillator period and for a 0.2s oscillator period will be developed using probabilistic approached. The model of seismic sources will be developed based on the latest data and information in Indonesia such as PusGeN (National Center for Earthquake Studies) and/or published paper. Case studies were taken in the offshore areas of North Java to the Sunda Strait and Sumatra Waters. Based on the results of this study, it is known that most of the areas fall into zone 4, which according to ISO 19901-2 falls into seismic risk category 3 or 4. According to ISO 19901-2 categories, detailed seismic action procedures and evaluation of seismic activities using site-specific hazards are required. analysis and non-linear abnormal earthquake level (ALE) analysis.
Penerapan Karya Tulis
Currently, there is no standard code in designing earthquake resistance structures for offshore platforms in Indonesia.