Seismic action

Slope NX includes seismic action with the pseudo-static approach: to each slice weight it adds a horizontal force k_h·W and a vertical one k_v·W, where k_h and k_v are the seismic coefficients.

Enable Seismic analysis in the Analysis → Method and parameters panel.

Manual coefficients or from NTC

You can enter k_h and k_v manually (useful for EC/LRFD/User), or compute them to NTC from the seismic panel:

• Subsoil category (A–E) and topographic category (T1–T4).
• Use class and nominal life (V_N) → reference period.
• Hazard parameters: a_g/g (SLV), F₀, T_C*.

The computation returns a_max, the reduction coefficient β and the coefficients k_h = β·a_max/g and k_v = ±0.5·k_h (per the code coefficients for soils and structures).

Import from GeoStru PS

If you have already computed the hazard with GeoStru Spectra (or an equivalent tool), you can import the seismic-parameters file (.txt) and Slope NX fills in k_h/k_v automatically.

Threshold in seismic conditions

With characteristic parameters (traditional method) the reference FoS values drop to 1.1–1.3 in the presence of an earthquake. With partial factors at limit states the verification remains satisfied for FoS ≥ 1.0.

---

Found an error on this page? Let us know or open a Pull Request.