PSI - Issue 84

Giovanni Stasi et al. / Procedia Structural Integrity 84 (2026) 789–796

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Fig. 7. Interaction domain of the base section of pier 4 shear wall.

In this way, the ratio between capacity and demand at combined compressive and bending stress of one of the 4 partitions of the highest pile, pile 4, is FS = 1.14 as shown in the following graph.

Fig. 8. Eccentricity of actions – combination PP+PERM+0.5*(0.3EX+EY).

In order to reduce the eccentricities of the bending moments relative to the axial force and to bring them back inside and near the central core of inertia of the pier footings, it is necessary to reduce the seismic action of the spectrum by about 50% on type A soil. The following image shows the footprints of the pile plinths with the representative points of the aforementioned eccentricities with a 50% reduced elastic spectrum (  E = 0.5). A graph is shown with the standard spectra at the SLC on type A subsoil with variable damping between 5% and 40% in the ADSR plane and two inclined lines at the periods equal to T = 1.15s and T = 3.5s. It can be seen that the accelerations and displacements are reduced by about 40 and 60% respectively, passing from a damping of 5% to one of 20%. In light of these results, an attempt was made to define an energy isolation and dissipation system capable of reducing the effects by at least 50% both in terms of stresses and displacements.

Fig. 9. Standard SLC spectra (Type A soil) in ADSR format for variable damping and specific periods (T = 1.15s, 3.5s).