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Tutorial 8 — Wind & Seismic Loads (Pro)

Occasional loads ride on top of the operating state: the solver first converges OPE (with friction and lift-off), then superposes the wind/seismic increment with the contact state frozen and any snubbers locked.

Model: a tall vertical run works best — e.g. anchor at grade, dZ 12 riser, elbow, dX 6 horizontal with a rest + guide, anchor. DN150, T_max 120 °C.

Wind — AS 1170.2 (or ASCE 7)​

  1. Settings → Wind Load Settings → code AS 1170.2.
  2. Regional wind speed V_R 45 m/s, Terrain Category 2, M_d 1.0, M_t 1.0, angle 0° (wind along +X).
  3. The Load Case list now includes OCC-WIND, and Run All Cases shows one more case.
  4. Run OCC-WIND. The wind pressure varies with elevation and acts on the projected diameter (coating included) — the tall riser collects most of it.
  5. Pipe Stresses: occasional rows are checked against 1.33 × Sh. Reactions: the guide now carries the lateral wind share.

Switch the code dropdown to ASCE 7 to see the US-style inputs (V, exposure B/C/D) — same workflow.

Seismic — static equivalent​

  1. Settings → Seismic Load Settings → code GENERIC.
  2. G-factor 0.25, Direction X.
  3. Run OCC-SEIS: every element's mass (steel + fluid + coating + valve/actuator masses) is loaded at 0.25 g horizontally.
  4. Valves with an actuator offset generate eccentric torsion — model actuated valves with their real CoG offsets.
  5. A Dynamic Snubber placed on the riser locks for this case only — compare its reaction between OPE (zero) and OCC-SEIS.

The AS 1170.4 option computes the g-factor from kp, hazard factor Z, site class and ac/rc instead.

Modal analysis — know your frequencies​

  1. Settings → Modal Analysis → Run Modal Analysis. The fundamental frequency is announced; the viewer's Modal Analysis pill animates each mode (pick the mode, set exaggeration, pause/play).
  2. Read the mass participation table: a mode with high X-participation is the one wind/seismic in X excites. Rule of thumb: keep piping fundamental frequencies above ~4–5 Hz where practical, and capture ≥ 90 % cumulative participation per direction if you take these results into a response-spectrum evaluation elsewhere.

Reporting​

Run All Cases now includes the occasional cases in the envelope page — one PDF covers the lot. Modal runs produce their own dedicated report pages (frequencies + participation) when the modal results are active.