Efficiency of seismic isolation on industrial plants - Case study of a gas tank

Recent earthquakes such as the one in Fukushima in Japan in 2011 highlighted the need of providing adequate protection to industrial installations. To answer this need, the ongoing RFCS research project PROINDUSTRY is addressing the question of the development of innovative seismic protection systems, both for the design of new industrial plants and for the retrofit of existing ones. This paper presents a specific aspect of the ongoing investigations within the referred project, namely a case study considering a Gas Tank. The protection systems under development contemplate both seismic isolation and energy dissipation techniques. For the presented case study, the base isolation system under development was finally chosen to improve the seismic performance of the Tank structure. In order to characterize the behavior of the Gas Tank structure, several numerical simulations were performed comprising modal analyses, push-over analyses and time-history nonlinear analyses. For the time-history nonlinear analysis ground motions were generated on the basis of available information on ground motion histories from national, European and Mediterranean Strong Motion Data-bases. Finally, the efficiency of the base isolation used in the Gas Tank structure is investigated by comparing the results of the time-history nonlinear analysis on the protected and the non-protected structure.