Calculation
The existing storage tanks have been subjected to seismic analysis to comply with the French regulation “Classified Installations for the Protection of the Environment (ICPE)”. Initially, the spheres were designed according to the French seismic code PS92, using the site‑specific response spectrum. However, Eurocode 8 and the Decree of October 4, 2010 have redefined the design spectrum, specifying the seismic rules for installations classified as involving risks. Therefore, new analysis of the butadiene sphere was required.Structure and Modeling
The storage sphere is supported by eleven steel columns welded around the envelope of the structure. The columns are interconnected by a bolted circumferential ring. Braces ensure increased horizontal stability of the storage sphere in cases of wind and seismic loads.A 3D model was created in the structural engineering software RFEM. All the components were entered as surface elements (spherical envelope, columns, circumferential ring, braces, gusset plates, anchor plates, and other components). The soil-structure interaction was taken into account by using elastic supports, transferring the stiffness of the deep foundations in each spatial direction.
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