feat: initial otko import

examples/moment_curvature.py

@@ -0,0 +1,249 @@
+"""Moment-Curvature Example — OpenSees Examples Manual, Example 2.
+
+Reinforced-concrete column cross-section, fibre discretisation, axial
+preload + monotonic moment pushover. Mirrors the OpenSees Tcl script
+at https://opensees.berkeley.edu/wiki/index.php?title=Moment_Curvature_Example
+
+Model
+-----
+Two coincident nodes linked by a ``zeroLengthSection`` carrying the
+RC fibre section. Node 1 is fully restrained; node 2 is free in Ux
+(so axial can shorten) and Rz (the curvature DOF). A constant axial
+load P = -180 kip is applied first via LoadControl(0); then a
+linear reference moment pattern (Mz = 1 kip·in) is added and
+DisplacementControl on DOF 3 ramps the curvature to μ·Ky where
+μ = 15 and Ky is the elastic yield curvature estimate.
+
+Units: kip, in, ksi (UnitSystem.US_IN_KIP).
+
+GUI walkthrough: File → Open → moment_curvature.osmodel, Options →
+Set Display Units → US (in, kip, kip·s²/in, s, ksi), Analyze → Run →
+MK, Display → Show Pushover Curve.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+from otko.core import (
+    Concrete01,
+    ConstantTimeSeries,
+    CoordinateGridSystem,
+    FiberSection,
+    GridSystem,
+    LinearTimeSeries,
+    NodalLoad,
+    Node,
+    PlainLoadPattern,
+    Project,
+    ProjectMeta,
+    PushoverCase,
+    RectangularPatch,
+    Steel01,
+    StraightLayer,
+    UnitSystem,
+    ZeroLengthSectionElement,
+    make_grid_lines,
+)
+from otko.services import load_project, save_project
+
+
+# Cross-section parameters (kip-in-ksi, from the Tcl example).
+COL_WIDTH = 15.0     # z-direction dimension
+COL_DEPTH = 24.0     # y-direction dimension
+COVER = 1.5
+AS_BAR = 0.60        # area of one #7 rebar
+
+FY = 60.0            # steel yield stress, ksi
+E_STEEL = 30000.0    # steel Young's modulus, ksi
+HARDENING = 0.01     # strain-hardening ratio
+
+P_AXIAL = -180.0     # kip, compression
+MU = 15              # target curvature ductility
+NUM_INCR = 100       # DisplacementControl increments
+
+
+def build_moment_curvature() -> Project:
+    """Build the OpenSees Example 2 Moment-Curvature project."""
+    y1 = COL_DEPTH / 2.0     # 12
+    z1 = COL_WIDTH / 2.0     # 7.5
+    d = COL_DEPTH - COVER    # 22.5
+
+    # Yield curvature estimate, assumed elastic + top/bottom steel only.
+    eps_y = FY / E_STEEL                # 0.002
+    ky = eps_y / (0.7 * d)              # ≈ 1.27e-4
+    max_k = ky * MU                     # ≈ 1.905e-3
+    d_k = max_k / NUM_INCR              # per-step curvature increment
+
+    return Project(
+        meta=ProjectMeta(
+            name="Moment-Curvature (OpenSees Ex 2)",
+            author="OpenSees Examples Manual",
+            description=(
+                "RC column fibre section — constant axial P + DisplacementControl "
+                "curvature pushover. Kip-in-ksi units throughout."
+            ),
+            units=UnitSystem.US_IN_KIP,
+        ),
+        ndm=2, ndf=3,
+        coord_systems=[
+            # A tiny grid at the section origin so the two coincident
+            # nodes have a visual anchor in the canvas.
+            CoordinateGridSystem(
+                name="Global",
+                grid=GridSystem(
+                    x_grid_lines=make_grid_lines("X", [0.0]),
+                    y_grid_lines=make_grid_lines("Y", [0.0]),
+                    z_grid_lines=make_grid_lines("Z", [0.0]),
+                ),
+            ),
+        ],
+        nodes=[
+            # Node 1 — fully clamped.
+            Node(id=1, name="Support",
+                 coords=(0.0, 0.0, 0.0),
+                 restraint=(True, True, False, False, False, True)),
+            # Node 2 — free in Ux and Rz (axial + curvature).
+            Node(id=2, name="Crown",
+                 coords=(0.0, 0.0, 0.0),
+                 restraint=(False, True, False, False, False, False)),
+        ],
+        materials=[
+            # Core concrete — confined (tag 1).
+            Concrete01(id=1, name="Core-Conc",
+                       fpc=-6.0, epsc0=-0.004,
+                       fpcu=-5.0, epsU=-0.014),
+            # Cover concrete — unconfined (tag 2).
+            Concrete01(id=2, name="Cover-Conc",
+                       fpc=-5.0, epsc0=-0.002,
+                       fpcu=0.0, epsU=-0.006),
+            # Reinforcing steel — bilinear hardening (tag 3).
+            Steel01(id=3, name="Steel-60",
+                    Fy=FY, E0=E_STEEL, b=HARDENING),
+        ],
+        sections=[
+            FiberSection(
+                id=1, name="RC-Column",
+                patches=[
+                    # Core — confined concrete inside the rebar ring.
+                    RectangularPatch(
+                        material_id=1, n_fib_y=10, n_fib_z=1,
+                        y_i=COVER - y1, z_i=COVER - z1,
+                        y_j=y1 - COVER, z_j=z1 - COVER,
+                    ),
+                    # Top cover (unconfined).
+                    RectangularPatch(
+                        material_id=2, n_fib_y=10, n_fib_z=1,
+                        y_i=-y1, z_i=z1 - COVER,
+                        y_j=y1, z_j=z1,
+                    ),
+                    # Bottom cover.
+                    RectangularPatch(
+                        material_id=2, n_fib_y=10, n_fib_z=1,
+                        y_i=-y1, z_i=-z1,
+                        y_j=y1, z_j=COVER - z1,
+                    ),
+                    # Left cover.
+                    RectangularPatch(
+                        material_id=2, n_fib_y=2, n_fib_z=1,
+                        y_i=-y1, z_i=COVER - z1,
+                        y_j=COVER - y1, z_j=z1 - COVER,
+                    ),
+                    # Right cover.
+                    RectangularPatch(
+                        material_id=2, n_fib_y=2, n_fib_z=1,
+                        y_i=y1 - COVER, z_i=COVER - z1,
+                        y_j=y1, z_j=z1 - COVER,
+                    ),
+                ],
+                layers=[
+                    # Top rebar (3 × #7).
+                    StraightLayer(
+                        material_id=3, n_bars=3, bar_area=AS_BAR,
+                        y_start=y1 - COVER, z_start=z1 - COVER,
+                        y_end=y1 - COVER, z_end=COVER - z1,
+                    ),
+                    # Middle rebar (2 × #7).
+                    StraightLayer(
+                        material_id=3, n_bars=2, bar_area=AS_BAR,
+                        y_start=0.0, z_start=z1 - COVER,
+                        y_end=0.0, z_end=COVER - z1,
+                    ),
+                    # Bottom rebar (3 × #7).
+                    StraightLayer(
+                        material_id=3, n_bars=3, bar_area=AS_BAR,
+                        y_start=COVER - y1, z_start=z1 - COVER,
+                        y_end=COVER - y1, z_end=COVER - z1,
+                    ),
+                ],
+            ),
+        ],
+        elements=[
+            ZeroLengthSectionElement(
+                id=1, name="MK-Link",
+                nodes=(1, 2), section_id=1,
+            ),
+        ],
+        time_series=[
+            ConstantTimeSeries(id=1, name="AxialP"),
+            LinearTimeSeries(id=2, name="RefMoment"),
+        ],
+        load_patterns=[
+            # Constant axial preload at node 2 — Fx = P (compression).
+            PlainLoadPattern(
+                id=1, name="AxialP",
+                time_series_id=1,
+                nodal_loads=[
+                    NodalLoad(node_id=2,
+                              forces=(P_AXIAL, 0, 0, 0, 0, 0)),
+                ],
+            ),
+            # Linear reference moment — Mz = 1.0, DisplacementControl
+            # scales this as it ramps curvature.
+            PlainLoadPattern(
+                id=2, name="RefMoment",
+                time_series_id=2,
+                nodal_loads=[
+                    NodalLoad(node_id=2,
+                              forces=(0, 0, 0, 0, 0, 1.0)),
+                ],
+            ),
+        ],
+        analyses=[
+            PushoverCase(
+                id=1, name="MK",
+                pattern_ids=[1, 2],
+                control_node=2, control_dof=3,    # Rz = curvature
+                target_disp=max_k,
+                step_size=d_k,
+                base_nodes=[1],
+                test="NormUnbalance",
+                tolerance=1e-9, max_iter=25,
+            ),
+        ],
+    )
+
+
+def main() -> None:
+    project = build_moment_curvature()
+    project.validate_references()
+    y1 = COL_DEPTH / 2.0
+    eps_y = FY / E_STEEL
+    ky = eps_y / (0.7 * (COL_DEPTH - COVER))
+    print(f"Built '{project.meta.name}'")
+    print(f"  ndm={project.ndm}, ndf={project.ndf}, units={project.meta.units.value}")
+    print(f"  Estimated yield curvature Ky = {ky:.4e} 1/in")
+    print(f"  Target (mu * Ky) = {ky * MU:.4e} 1/in   (mu = {MU})")
+
+    out_path = Path(__file__).with_suffix(".osmodel")
+    save_project(project, out_path)
+    print(f"Saved -> {out_path}")
+
+    restored = load_project(out_path)
+    restored.validate_references()
+    assert restored.model_dump(by_alias=True) == project.model_dump(by_alias=True)
+    print("Round-trip OK.")
+
+
+if __name__ == "__main__":
+    main()