Use when driving OpenSeesPy (PEER's structural earthquake-engineering FEM framework) via Python scripts — elastic/inelastic beams, fiber sections, nonlinear pushover, time-history seismic analysis, eigenvalue/modal — through sim runtime one-shot execution.
You are connected to OpenSeesPy via sim-cli.
OpenSees (Open System for Earthquake Engineering Simulation) is the structural / geotechnical FEM framework developed at PEER (UC Berkeley). OpenSeesPy is the Python interpreter wrapper, distributed as pip wheels:
openseespy — pure Python facadeopenseespylinux / openseespywin / openseespymac — compiled coreScripts are plain .py:
import openseespy.opensees as ops
ops.wipe()
ops.model('basic', '-ndm', 2, '-ndf', 3)
ops.node(...); ops.element(...)
ops.timeSeries(...); ops.pattern(...); ops.load(...)
ops.system(...); ops.numberer(...); ops.constraints(...)
ops.integrator(...); ops.algorithm(...); ops.analysis(...)
ops.analyze(N)
disp = ops.nodeDisp(node, dof)
Same subprocess driver mode as PyBaMM / PyMFEM / scikit-fem.
| Path | What's there |
|---|
base/reference/workflow.md | Standard analysis workflow — model → loads → analysis options → analyze → query. |
base/reference/model_dim.md | ndm/ndf choices and their DOF semantics (1D/2D/3D). |
base/reference/elements.md | truss / elasticBeamColumn / forceBeamColumn / quad / brick. |
base/reference/analysis.md | Static / Transient / EigenAnalysis; system/numberer/algorithm/integrator combos. |
base/snippets/01_cantilever.py | Verified elastic cantilever tip-deflection E2E. |
base/known_issues.md | Process 0 Terminating stderr, wipe() between runs, fix DOF-count consistency. |
sdk/3/notes.md — version-specific API surface notes.ops.wipe() first. OpenSees holds global state across
model commands; not wiping leaks nodes / elements between runs.ndf must match every node/fix/load call. A 2D Euler-Bernoulli
beam needs ndm=2, ndf=3 (ux, uy, rotz). A 2D truss needs ndm=2, ndf=2
(ux, uy). Mismatched DOF counts silently corrupt boundary conditions.system → numberer → constraints → integrator → algorithm → analysis.
Skipping any of these gives "analysis object not constructed" errors.ops.analyze(N) returns 0 on
success, non-zero on failure — but always also validate against an
analytical/benchmark result (tip deflection, period, mode shape, ...).Process 0 Terminating to stderr on every interpreter exit, even on
success. Use the analyze() return code and JSON output instead.BandSPD, UmfPack, ...).sim check openseespy to confirm the wheel is importable..py script following the workflow in base/reference/workflow.md.sim lint script.py to catch missing import / syntax / no-usage warnings.sim run script.py --solver openseespy for one-shot execution.