A 3000 tones capacity silo, located in a seismic area with ground acceleration ag = 0,20g and TC =1,0s, was designed in a classical solution The supporting structure has an octagonal shape in planview, and columns with “Maltese cross sections”. The main lateral resisting system is made up of centric bracings with cross-section class I.
The technological project has required two silos and the solution was to support them on a common raft foundation. The stresses and strains due the seismic action led to material consumption that exceeded the agreed budget. In order to reduce the costs, two versions of isolator positions were studied: base isolators (at the connection between infrastructure and superstructure) and at the silo’s bearing level on the supporting structure.
A number of eight vertical seismic isolators were used and in order to limit the horizontal displacements due to wind action and for small intensity earthquakes special devices were introduced
Comparing the state of stresses and deformations and also the cost analysis regarding the positioning of the isolators, the second solution was chosen as the most feasible.