feat: initial otko import

tests/integration/test_concrete04_runner.py

@@ -0,0 +1,148 @@
+"""Integration test: Concrete04 in a fiber-section cantilever.
+
+Verifies that the full stack (model → runner → OpenSeesPy → result) works
+end-to-end with Concrete04 (Popovics concrete) as the sole material.
+
+Reference: for very small compressive strains the Popovics curve is
+linear with slope Ec, so the axial shortening of a column under a
+small axial load is:
+
+    delta = P * L / (Ec * A)
+
+with negligible Popovics nonlinearity at the applied strain level.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+pytest.importorskip("openseespy")
+
+from otko.core import (  # noqa: E402
+    Concrete04,
+    FiberSection,
+    ForceBeamColumn,
+    LinearTimeSeries,
+    NodalLoad,
+    Node,
+    PlainLoadPattern,
+    Project,
+    ProjectMeta,
+    RectangularPatch,
+    StaticCase,
+    UnitSystem,
+)
+from otko.services.opensees_runner import OpenSeesRunner  # noqa: E402
+
+# ── Model constants ────────────────────────────────────────────────────────────
+L = 1.0          # column height [m]
+B = H = 0.3      # cross-section dimensions [m]
+A = B * H        # section area [m²]
+
+FC = -30e6       # peak compressive strength [Pa]  (negative)
+EPSC0 = -0.002   # strain at peak strength          (negative)
+EPSCU = -0.005   # ultimate compressive strain      (negative)
+EC = 30e9        # initial tangent modulus [Pa]
+
+# Applied axial load: small enough (< 1 % of capacity) that the Popovics
+# curve is indistinguishable from its linear tangent at origin.
+P_AXIAL = -1200.0   # N  (downward → compressive)
+
+# Analytical axial shortening: P * L / (Ec * A)
+EXPECTED_UY = P_AXIAL * L / (EC * A)   # ≈ -1.333e-7 m
+
+
+def _build_project() -> Project:
+    return Project(
+        meta=ProjectMeta(
+            name="Concrete04 fiber-section cantilever",
+            units=UnitSystem.SI_M_N,
+        ),
+        ndm=2,
+        ndf=3,
+        nodes=[
+            Node(id=1, name="Base", coords=(0.0, 0.0, 0.0),
+                 restraint=(True, True, True, False, False, False)),
+            Node(id=2, name="Top",  coords=(0.0, L, 0.0)),
+        ],
+        materials=[
+            Concrete04(
+                id=1, name="C30-Popovics",
+                fpc=FC, epsc0=EPSC0, epscu=EPSCU, Ec=EC,
+            ),
+        ],
+        sections=[
+            FiberSection(
+                id=1, name="RC-Fiber",
+                patches=[
+                    RectangularPatch(
+                        material_id=1,
+                        n_fib_y=4, n_fib_z=4,
+                        y_i=-H / 2, z_i=-B / 2,
+                        y_j= H / 2, z_j= B / 2,
+                    ),
+                ],
+            ),
+        ],
+        elements=[
+            ForceBeamColumn(
+                id=1, name="Column",
+                nodes=(1, 2),
+                section_id=1,
+                integration_points=3,
+                geom_transf="Linear",
+            ),
+        ],
+        time_series=[LinearTimeSeries(id=1, name="Ramp")],
+        load_patterns=[
+            PlainLoadPattern(
+                id=1, name="Gravity", time_series_id=1,
+                nodal_loads=[
+                    NodalLoad(node_id=2, forces=(0.0, P_AXIAL, 0.0, 0.0, 0.0, 0.0)),
+                ],
+            ),
+        ],
+        analyses=[
+            StaticCase(
+                id=1, name="Gravity",
+                pattern_ids=[1],
+                n_steps=1,
+                load_factor_increment=1.0,
+                system="BandGeneral",
+                constraints="Plain",
+                integrator="LoadControl",
+                algorithm="Newton",
+                test="NormDispIncr",
+                tolerance=1e-12,
+                max_iter=10,
+            ),
+        ],
+    )
+
+
+def test_concrete04_gravity_axial_shortening() -> None:
+    """Axial shortening under small gravity load matches the linear reference."""
+    proj = _build_project()
+    case = proj.analyses[0]
+    result = OpenSeesRunner(proj).run(case)
+
+    # Uy at the top node (DOF index 1 = Y in 2D 3-DOF).
+    uy = result.node_disp[2][0, 1]
+
+    # Tolerance: 0.1 % relative — the Popovics curve at the applied strain
+    # level (|ε| ≈ 1.5e-8) deviates from linear by < 1e-12 relative.
+    assert uy == pytest.approx(EXPECTED_UY, rel=1e-3)
+
+
+def test_concrete04_with_tension_does_not_raise() -> None:
+    """Smoke-test: optional tensile branch accepted by OpenSeesPy without error."""
+    proj = _build_project()
+    # Replace material with tensile-branch variant.
+    proj.materials[0] = Concrete04(
+        id=1, name="C30-WithTension",
+        fpc=FC, epsc0=EPSC0, epscu=EPSCU, Ec=EC,
+        fct=3.0e6, et=1e-4,
+    )
+    case = proj.analyses[0]
+    result = OpenSeesRunner(proj).run(case)
+    assert result.node_disp[2][0, 1] == pytest.approx(EXPECTED_UY, rel=1e-3)