PSI - Issue 78

Lorenzo Audisio et al. / Procedia Structural Integrity 78 (2026) 1277–1284

1283

• Petrone-Magliulo-Manfredi , blue line (Petrone et al., 2015); • Degli Abbati-Cattari-Lagomarsino , green line (Abbati et al., 2018); • Eurocode 8 , cyan line (CEN 2004) • Calvi-Sullivan , magenta line (Calvi & Sullivan, 2014).

Figure 5 highlights a good agreement between the results obtained with the proposed formulation and the ones derived with the FEM analyses. Compared to the other analytical formulations considered, the proposed model proves to be more accurate in reproducing both the magnitude and the position of the amplification peak, especially on the upper floors, where the influence of higher vibration modes becomes more pronounced. The other formulations tend to either overestimate or underestimate the acceleration demand in some case, confirming the higher predictive consistency of the proposed model relative to the numerical reference. 5. Conclusions In this study, the derivation of the amplification factor R, used for estimating the Floor Response Spectrum (FRS) of acceleration-sensitive NSEs is presented. The proposed expression, adopted by the Italian code, is derived from the dynamic behavior of a damped single-degree-of-freedom oscillator subjected to harmonic excitation and incorporates both the modal response of the supporting structure and the dynamic properties of the NSE. The formulation was calibrated through an extensive set of linear parametric analyses conducted on coupled two degree-of-freedom models. This process led to the identification of optimal coefficients capable of effectively reproducing the seismic amplification experienced by NSEs across a wide range of configurations. The numerical results obtained from FEM simulations, where the NSEs are modeled using frame elements with lumped masses confirm the model’s accuracy. In particular, the proposed formulation successfully captures the resonance peak and its sensitivity to both structural and non-structural parameters. It is important to note that this study does not account for structural non-linearities or epistemic and aleatory uncertainties, such as the variability of the NSE natural period. These aspects may significantly influence the seismic demand on non-structural components and should be explicitly considered in future developments of the methodology here discussed. References Abbati, S. D., Cattari, S., & Lagomarsino, S. (2018). Theoretically-based and practice-oriented formulations for the floor spectra evaluation. Earthquake and Structures, 15(5), 565 – 581. https://doi.org/10.12989/eas.2018.15.5.565 Anil k. Chopra. (1995). Dynamics of Structures Theory and Applications to Earthquake Engineering (Prentice Hall). Biggs, J. M. (1971). Seismic response spectra for equipment design in nuclear power plants. In First International Conference on Structural Mechanics in Reactor Technology, Berlin (pp. p329-343). Braga, F., Manfredi, V., Masi, A., Salvatori, A., & Vona, M. (2011). Performance of non-structural elements in RC buildings during the L’Aquila, 2009 earthquake. Bulletin of Earthquake Engineering, 9(1), 307– 324. https://doi.org/10.1007/s10518-010-9205-7 Calvi, P. M., & Sullivan, T. J. (2014). Estimating floor spectra in multiple degree of freedom systems. Earthquake and Structures, 7(1), 17 – 38. https://doi.org/10.12989/eas.2014.7.1.017 Chen, C. (1974). Seismic resistant design of safety class structures and equipment. Nuclear Engineering and Design, 30(1), 100 – 110. https://doi.org/10.1016/0029-5493(74)90155-1 MIT - Ministro delle infrastrutture e dei Trasporti Circ. C.S.Ll. 21 gennaio 2019 n. 7. Istruzioni per l’applicazione dell’«Aggiornamento delle “Norme tecniche per le costruzioni”» di cui al decreto ministeriale 17 gennaio 2018; (2019). MIT - Ministro delle Infrastrutture e dei Trasporti - Decreto 17 gennaio 2018: Aggiornamento delle “Norme Tecniche per le costruzioni”; (2018). Eurocode 8: EN 1998-1:2004. Design of structures for earthquake resistance. Part 1- 1: General rules – Seismic actions and general requirements for structures. Brussels, Belgium; 2004. (n.d.).