Add structural calculation worksheets

Collection of engineering calculation projects (Python + Typst), each with
input, calc script, tests, results, and generated PDF where available.

concrete-beam2/test_concrete_beam2.py

@@ -0,0 +1,70 @@
+from pathlib import Path
+import importlib.util
+
+import pytest
+import yaml
+
+
+HERE = Path(__file__).resolve().parent
+
+spec = importlib.util.spec_from_file_location("concrete_beam2_calc", HERE / "calc.py")
+assert spec is not None and spec.loader is not None
+calc_module = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(calc_module)
+compute = calc_module.compute
+
+
+def load_input():
+    with (HERE / "input.yaml").open(encoding="utf-8") as handle:
+        return yaml.safe_load(handle)
+
+
+@pytest.fixture
+def result():
+    return compute(load_input())
+
+
+def test_example_demands(result):
+    v = result["values"]
+    assert v["self_weight_klf"] == pytest.approx(0.1)
+    assert v["wu_klf"] == pytest.approx(0.7325)
+    assert v["Mu_kipft"] == pytest.approx(23.44)
+    assert v["Vu_kip"] == pytest.approx(5.86)
+
+
+def test_example_flexure(result):
+    v = result["values"]
+    assert v["a_in"] == pytest.approx(1.519608, rel=1e-5)
+    assert v["et"] == pytest.approx(0.017137, rel=1e-3)
+    assert v["phi"] == pytest.approx(0.9)
+    assert v["phiMn_kipft"] == pytest.approx(26.133456, rel=1e-5)
+    assert result["checks"]["flexure"]["ok"] is True
+
+
+def test_example_min_steel_and_shear(result):
+    v = result["values"]
+    assert v["As_min_in2"] == pytest.approx(0.384, rel=1e-4)
+    assert v["phiVc_kip"] == pytest.approx(7.887205, rel=1e-4)
+    assert result["checks"]["minimum_steel"]["ok"] is True
+    assert result["checks"]["shear"]["ok"] is True
+
+
+def test_alternate_units_match_default(result):
+    alt = load_input()
+    alt.update(
+        {
+            "span": "192 in",
+            "tributary": "75 in",
+            "fc": "3000 psi",
+        }
+    )
+    converted = compute(alt)
+    for key in ("span_ft", "tributary_ft", "fc_ksi", "Mu_kipft", "phiMn_kipft", "Vu_kip"):
+        assert converted["values"][key] == pytest.approx(result["values"][key], rel=1e-6)
+
+
+def test_wrong_dimension_is_rejected():
+    bad = load_input()
+    bad["span"] = "16 kip"
+    with pytest.raises(ValueError, match="span"):
+        compute(bad)