Abstract: To avoid the negative consequences of the anticipated depletion of the Malampaya gas field by 2027, the Philippines urgently needs to import liquefied natural gas (LNG). The government has given the go-ahead to three LNG import terminal projects that will initiate operations this year, signaling the country’s entry into the LNG industry.
Constructing the LNG terminal is paramount in guaranteeing the security of the country's energy grid and providing support for the advancement of renewable energy. It will play a crucial role in helping the Philippines shift from relying on fossil fuels to utilizing green energy.
Although the ground conditions at the project site were challenging (with considerable liquefaction depths of up to 30 meters), coupled with the Philippines' high seismic activity and the importance level that mandates earthquake-proof design capable of withstanding a 2475-year earthquake, several hurdles had to be overcome. Due to these significant obstacles, a bespoke analysis and design framework was developed drawing from multiple technical sources and various technical experts across the globe.
The Jetty is located adjacent to the existing jetty and is capable of receiving liquid fuel carriers, LNG carriers, FSRU and FSUs. The new jetty structures comprise a total of 10,000 MT (212 no) tubular steel piles ranging from 45 – 65 m in length. The superstructure comprises approximately 15,500 MT of fabricated steel jackets and deck/trestle modules. The Loading Platform is topped by a reinforced concrete deck slab which accommodates 2 ship gangways, 3 HP Gas Unloading Arms and a jib crane, among its critical deck equipment.
The facility is now constructed and operational.
How does this project / topic contribute to the advancement of the industry and profession?: The pioneering project in the Philippines is vital in safeguarding the security of the energy grid and promoting the growth of green energy sources, thereby facilitating the country's shift from non-renewable energy sources to sustainable ones. The seismic and soil-structure interaction framework developed as part of this project uses specialized technical knowledge that can be applied to other highly seismic regions facing similar challenges. The experience gained from this project is directly transferable to marine facilities that transport other zero carbon fuels like hydrogen and ammonia as these also require liquid form transportation.
Does the project / topic implement new and innovative techniques, materials, technologies, and delivery methods?: Yes. The developed framework is capable of meeting both the rigorous seismic and liquefaction requirements. The design approach utilized a force-based method for ensuring operational functionality during a 475-year earthquake while simultaneously achieving the necessary inelastic performance requirements for collapse prevention during a 2475-year earthquake through a displacement-based method. Pushover analysis and fiber inelastic hinges were used to capture the inelastic behavior of piles, joint cans, and bracings. Spectrally-matched time histories were used for ground response analysis to determine the liquefied and non-liquefied response spectra and soil displacements.
What was the most challenging aspect of your project / topic and how did you handle it to ensure success?: Although there are marine seismic design codes and guidelines available, none provide a comprehensive framework that fully captures both inelastic performance design and liquefaction for an LNG facility. This challenge made economical design very hard to attain using conventional and often empirical design methods. This necessitated the development of a practical and robust but innovative technical framework by drawing from multiple technical sources and various experts across the globe.
Who is the target audience for this paper?: Fellow marine structural engineers who are interested in a framework that will allow them to tackle very challenging seismic and liquefaction conditions specially with very stringent seismic performance requirements like LNG facilities.
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