Hendriyawan
Two earthquake levels were introduced in the code; i.e. Strength Level Earthquakes (SLE) and Ductility Level Earthquake (DLE). However, these guidelines do not explicitly state the return periods and the procedures for developing those two levels of earthquakes. ISO 19901-2 has a clearer procedure in determining the earthquake burden used for seismic analysis for offshore structures. Two levels of seismic design were used in ISO guidelines: Extreme Level Earthquakes (ELE) and Abnormal Level Earthquake (ALE). There are two alternative procedures were proposed in ISO 19901-2 for developing those two levels of earthquake; the simplified method, and the detailed method. A simplified method may be used when seismic considerations are unlikely to govern the design of a structure, while the detailed method may be used when seismic considerations have a significant impact on the design [1]. This paper presents the development 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 a probabilistic approach. The model for seismic sources will be developed based on the latest data and information in Indonesia such as from PusGeN (National Center for Earthquake Studies) and/or published paper.
Penerapan Karya Tulis
Earthquake is one of the natural disasters in the world that has claimed many lives and materials. The impact caused by an earthquake will generally increase significantly along with the increase in population growth in an area, especially in very active tectonic regions such as Indonesia. Currently, there is no standard code in designing earthquake-resistance structures for offshore platforms in Indonesia. Most platforms in Indonesia use API RP 2A WSD as a standard code for designing offshore structures.