PSI - Issue 78

Giovanni Smiroldo et al. / Procedia Structural Integrity 78 (2026) 1585–1592

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(a)

(b)

(c) Fig. 5. PGV comparisons for categories (a) A, (b) B and (c) C shallow soil structures.

5. Results and conclusion For sake of clarity, the spectral acceleration at a period equal to 0.5 s is shown as the result for a magnitude of 6.0, but similar plots are obtained for the investigated range of periods (0.1 – 0.5 – 1.0 – 2.0 seconds) and magnitudes. The comparisons demonstrate a strong agreement between physics-based simulated ground motions and observations derived from energy-based GMPEs. Most simulated values lie within 1 × standard deviation of the GMPE median, indicating that residuals are generally less than 1. This reflects the good predictive performance of the simulations across varying distances. However, larger deviations are observed within the first 10 km — likely due to the scarcity of real near-field recordings — and beyond 50 km, which may be attributed to the soil's shear velocity quality factor ( Q s ) affecting wave attenuation. Thus, the PBS database here created fits very well the real (observed) data in terms of released energy. For a more complete overview of the methodology, using different intensity measures and GMPEs, the reader can refer to (Smiroldo, 2025).