Impact and Mitigation of seismic SURFace waves on large 3D structures

Originality and Relevance

IM-SURF's originality lies in systematically bridging four scales — wave-regime characterisation, geological, geotechnical and structural — to move engineering practice from the simplified “3×1D” approximation toward full “3D” dynamic soil-structure interaction analysis, and in turning the results into concrete guidelines that define when the conventional 1D approach remains valid.

What sets IM-SURF apart

• Extending beyond long-period structures to massive structures of large dimensions with realistic foundation geometry — particularly large industrial and nuclear buildings, which can experience significant rotational motion from Rayleigh-wave incidence that 1D site-response analysis cannot capture.
• Completing the high-frequency content of the MODULATE database, most of whose signals were recorded with time steps too large to preserve high-frequency detail, using stochastic and AI methods together with additional signals from recent earthquakes (2023 Turkey, 2024 Noto).
• A novel hybrid ground-motion generation approach: rather than the usual practice of using only the low-frequency deterministic part of a signal to predict its high-frequency stochastic part, IM-SURF uses the middle-frequency (body-wave) range to predict both the low-frequency (surface-wave) and high-frequency parts — a technique rarely applied in the presence of surface waves.
• Advanced coupled numerical techniques across scales — the Spectral Element Method, H-matrix accelerated Boundary Element Method, Fourier Continuation-based solvers, and weak coupling schemes (SEM-FEM, SEM-SEM-FEM, BEM-FEM) — to preserve the full 3D wave regime, surface waves included, from the geological scale down to the structure.
• Nonlinear near-field and foundation effects integrated into the Domain Reduction Method, a technique already efficient and widely available in structural-analysis software but not yet thoroughly extended to surface-wave generation and near-foundation nonlinearity.
• Mitigation strategies aimed specifically at surface waves and rotational motion, including foundation retreat/treatment and periodic wave barriers that exploit elastic-wave “bandgaps,” as an alternative to structural upgrading when that isn't feasible or cost-effective.
• A direct, practice-ready deliverable: a concise set of rules and guidelines defining the validity range of conventional 1D site-response methods, and identifying which cases — by source characteristics, geological setup, geotechnical conditions and structural configuration — call for a rigorous 2D/3D approach instead.

See also: Context · Objectives · Impacts and Benefits