LNG Receiving Terminal Isolated Storage Tanks

SC Solutions was contracted by a large Oil and Gas company to perform a seismic assessment of two large vertical cylindrical LNG storage tanks located in the moderately high seismic region of southeastern coastal Italy.  SC Solutions performed a concept study to evaluate options for addressing seismic response challenges.  The study included the following considerations:

• geotechnical site evaluation
• site response analysis
• dynamic soil-structure interaction
• response spectrum analysis
• nonlinear time history analysis

To mitigate the effects of challenging site and design constraints, base isolation was proposed as an option to reduce seismic demand on the tank and foundation.  Detailed finite element models were built and analyses performed for two tank foundation configurations:

1. Tank supported directly on slab-on-grade
2. Tank supported by friction pendulum isolators on slab-on-grade

Analysis results demonstrated a reduction in foundation overturning moment of over 60% and a reduction in foundation shear of almost 70%.  Relative tank movement caused by isolation during an earthquake was mitigated by use of flexible piping connections.  The successful response reduction achieved by SC Solutions provided a feasible alternative to expensive foundation modifications and/or soil improvements.