WillTools 2026-09-09 -- clean snapshot of the development repo for review

History-free snapshot of the private development repository at cbe45c5 (2026-09-09). Code, docs and public catalogue only; no plant or job knowledge layers, no client or job names (tools/scrub.py clean). The intro deck is left out of this snapshot because its slide images could not be checked for job drawings.
2026-09-09 08:32:15 -05:00
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+# -*- coding: utf-8 -*-
+"""The insulated-sandwich SECTION path in `section.py` / `capacity.py`.
+
+Every expected number here is arithmetic done by hand, written out beside it,
+and -- where a golden figure exists -- pinned to the value Eriksson Wall's own
+section table prints, NOT to the code's own expression. A pin that recomputes
+both sides agrees with any refactor, including a wrong one.
+
+THE GOLDEN PIECE is WPB3.0 Run 1 (docs/eriksson-wall-algorithms.md sec.12 and
+the extracted `WPB3.0.md`): a horizontal insulated wall panel, layup
+
+    3 in. concrete + 4 in. insulation + 4 in. concrete  = 11 in. envelope
+
+at a clear width of 24 ft = 288 in (no opening at the checked station).
+Eriksson reports, for this section (p.11 of that packet):
+
+    Area 2016.00 in2   Cy 5.79 in   Izz 29955.43 in4   Sb 5177.48   St 5744.88
+
+which is the FULLY-COMPOSITE transformed section of the two concrete wythes
+about their common centroid, with the insulation EXCLUDED. That is what
+`section.NetSection` must reproduce for a sandwich, and it is what closes the
+"treated as a solid 11 in prism" defect: the solid idealisation would give
+Izz = 288*11^3/12 = 31944 and S = 288*11^2/6 = 5808, both larger than the real
+section (unconservative), and its shear b*d would be 288*0.8*11, a third too
+large -- see `test_shear_bd_drops_by_the_36_percent_the_parity_run_found`.
+
+The task framed Eriksson's treatment as NON-composite; the golden figures do
+not bear that out (Area 2016 is BOTH wythes, and Izz 29955 is their composite
+inertia, not one wythe's), so this implements and pins the composite section
+Eriksson actually reports. The %composite knock-down Eriksson then applies
+(95% for stress/strength, 35% for in-place deflection) and the strand
+development layer are out of scope here; the more conservative non-composite /
+structural-wythe-alone bounds live in `sandwich.py`.
+"""
+import math
+
+import pytest
+
+from panellift import capacity, section
+from panellift.model import Panel, Stage
+
+
+ENVELOPE = 11.0
+WIDTH_FT = 24.0
+B_IN = WIDTH_FT * 12.0            # 288 in
+
+
+def wpb3_source():
+    """`source` as the exporter writes it for the WPB3.0 layup.
+
+    3 in wythe at the form face (z 0-3), 4 in insulation (z 3-7), 4 in wythe
+    (z 7-11). The order does not change Area / Izz / the governing S; it only
+    labels which face is Sb and which is St.
+    """
+    return {
+        'solid_parts': [
+            {'counted': True, 'z0_in': 0.0, 'z1_in': 3.0,
+             'material': 'WYTHE 3IN', 'density_pcf': 150.0, 'volume_ft3': 1.0},
+            {'counted': False, 'z0_in': 3.0, 'z1_in': 7.0,
+             'material': 'INSULATION', 'density_pcf': 2.0, 'volume_ft3': 1.0},
+            {'counted': True, 'z0_in': 7.0, 'z1_in': 11.0,
+             'material': 'WYTHE 4IN', 'density_pcf': 150.0, 'volume_ft3': 1.0},
+        ],
+        'envelope_thickness_in': ENVELOPE,
+    }
+
+
+def wpb3_panel():
+    return Panel(mark='WPB3', length_ft=24.0, width_ft=WIDTH_FT,
+                 thickness_in=ENVELOPE, unit_weight_pcf=150.0,
+                 fci_psi=3500.0, fc_psi=6000.0, source=wpb3_source())
+
+
+def _mid_net(panel):
+    return section.NetSection(panel, panel.length_ft / 2.0)
+
+
+# ------------------------------------------------ the section, vs the golden
+
+def test_area_is_both_wythes_with_the_insulation_excluded():
+    # A = b * (t1 + t2) = 288 * (3 + 4) = 2016.00 in2, NOT 288*11 = 3168.
+    net = _mid_net(wpb3_panel())
+    assert net.is_sandwich is True
+    assert net.area_in2 == pytest.approx(2016.0, abs=1e-6)
+
+
+def test_centroid_is_the_composite_neutral_axis():
+    # zbar = (A1*z1 + A2*z2)/A, wythes at z=1.5 and z=9:
+    #   = (3*1.5 + 4*9)/7 = (4.5 + 36)/7 = 5.785714 in  ->  Eriksson Cy 5.79
+    net = _mid_net(wpb3_panel())
+    assert net.zbar_in == pytest.approx(5.7857143, abs=1e-6)
+
+
+def test_through_thickness_inertia_matches_the_reported_izz():
+    # Iz = b*[ t1^3/12 + t1*(z1 - zbar)^2 + t2^3/12 + t2*(z2 - zbar)^2 ]
+    #    = 288*[ 3^3/12 + 3*(1.5-5.785714)^2 + 4^3/12 + 4*(9-5.785714)^2 ]
+    #    = 288*[ 2.25 + 55.1020 + 5.3333 + 41.3265 ] = 288*104.0119 = 29955.4
+    net = _mid_net(wpb3_panel())
+    assert net.iz_in4 == pytest.approx(29955.43, abs=0.5)   # reported 29955.43
+
+
+def test_the_two_faces_have_the_unequal_moduli_eriksson_prints():
+    # c_form = 5.785714 (to z=0), c_far = 11 - 5.785714 = 5.214286 (to z=11)
+    #   Sb = 29955.43 / 5.785714 = 5177.5   (Eriksson 5177.48)
+    #   St = 29955.43 / 5.214286 = 5744.9   (Eriksson 5744.88)
+    net = _mid_net(wpb3_panel())
+    assert net.c_form_in == pytest.approx(5.7857143, abs=1e-6)
+    assert net.c_far_in == pytest.approx(5.2142857, abs=1e-6)
+    sb = net.iz_in4 / net.c_form_in
+    st = net.iz_in4 / net.c_far_in
+    assert sb == pytest.approx(5177.48, abs=1.0)
+    assert st == pytest.approx(5744.88, abs=1.0)
+    # sz_in3 is the GOVERNING (smaller) modulus, the one that decides tension.
+    assert net.sz_in3 == pytest.approx(min(sb, st), abs=1e-6)
+
+
+def test_the_solid_idealisation_would_have_overstated_this_section():
+    """The number the refusal was built on: the solid 11 in prism is bigger
+    than the real composite section, both in I and S -- unconservative."""
+    net = _mid_net(wpb3_panel())
+    solid_iz = B_IN * ENVELOPE ** 3 / 12.0            # 31944.0
+    solid_sz = B_IN * ENVELOPE ** 2 / 6.0             # 5808.0
+    assert solid_iz > net.iz_in4                       # 31944 > 29955
+    assert solid_sz > net.sz_in3                       # 5808 > 5177
+
+
+# --------------------------------------------------------------- shear b*d
+
+def test_shear_bd_drops_by_the_36_percent_the_parity_run_found():
+    """docs sec.3.1: for a sandwich d_v = 0.8*th uses the CONCRETE depth (the
+    summed wythes), not the envelope. Here that is 0.8*7 vs 0.8*11, so the
+    shear area is 7/11 of the solid one -- a 36.4% drop, which is exactly the
+    WPB3.0 shear residual the harness traced to b*d not excluding insulation.
+    """
+    net = _mid_net(wpb3_panel())
+    assert net.shear_thickness_in == pytest.approx(7.0)    # concrete, not 11
+    stage = Stage(name='strip', multiplier=1.4, fc_psi=3500.0)
+    pt = capacity.detailed_shear_at(wpb3_panel(), stage,
+                                    x=12.0, moment_lbft=5000.0, shear_lb=8000.0)
+    solid_bd = net.width_in * capacity.pci.DV_OVER_H_SHEAR * ENVELOPE
+    assert pt.bd_in2 == pytest.approx(solid_bd * 7.0 / 11.0, rel=1e-9)
+    drop = 1.0 - pt.bd_in2 / solid_bd
+    assert drop == pytest.approx(4.0 / 11.0, abs=1e-6)     # 0.3636...
+
+
+# --------------------------------------- contiguous two-layer -> merged solid
+
+def test_a_contiguous_two_concrete_body_is_the_merged_solid():
+    """An architectural face cast monolithically on a structural wythe (no
+    insulation gap) is not a hole in the middle -- its composite section is
+    simply the solid over the whole concrete span, and that is what comes
+    out. 4 in (z0-4) + 12 in (z4-16) contiguous -> a solid 16 in section."""
+    src = {'solid_parts': [
+        {'counted': True, 'z0_in': 4.0, 'z1_in': 16.0, 'material': 'STRUCT',
+         'density_pcf': 150.0, 'volume_ft3': 1.0},
+        {'counted': True, 'z0_in': 0.0, 'z1_in': 4.0, 'material': 'ARCH',
+         'density_pcf': 150.0, 'volume_ft3': 1.0}],
+        'envelope_thickness_in': 16.0}
+    panel = Panel(mark='C', length_ft=20.0, width_ft=5.0, thickness_in=12.0,
+                  source=src)
+    net = section.NetSection(panel, 10.0)
+    b = 5.0 * 12.0
+    assert net.area_in2 == pytest.approx(b * 16.0)         # all 16 in concrete
+    assert net.zbar_in == pytest.approx(8.0)               # mid-depth: solid
+    assert net.iz_in4 == pytest.approx(b * 16.0 ** 3 / 12.0)
+    assert net.shear_thickness_in == pytest.approx(16.0)
+
+
+# --------------------------------------------- the solid path does not move
+
+def test_a_solid_panel_is_untouched():
+    """No source -> not a sandwich -> the familiar b*t, b*t^2/6, b*t^3/12,
+    d_v = 0.8*t, centroid t/2. Byte-for-byte what it always was."""
+    panel = Panel(mark='S', length_ft=20.0, width_ft=5.0, thickness_in=8.0)
+    net = section.NetSection(panel, 10.0)
+    b = 5.0 * 12.0
+    assert net.is_sandwich is False
+    assert net.area_in2 == pytest.approx(b * 8.0)
+    assert net.zbar_in == pytest.approx(4.0)
+    assert net.c_form_in == pytest.approx(4.0)
+    assert net.c_far_in == pytest.approx(4.0)
+    assert net.iz_in4 == pytest.approx(b * 8.0 ** 3 / 12.0)
+    assert net.sz_in3 == pytest.approx(b * 8.0 ** 2 / 6.0)
+    assert net.shear_thickness_in == pytest.approx(8.0)
+
+
+def test_the_free_functions_follow_the_same_section():
+    """`section.area_in2` / `section_modulus_in3` / `inertia_in4` are what
+    `statics` (EI) and `layout` read; they must be the sandwich section too."""
+    panel = wpb3_panel()
+    x = 12.0
+    net = section.NetSection(panel, x)
+    assert section.area_in2(panel, x) == pytest.approx(net.area_in2, abs=1e-6)
+    assert section.inertia_in4(panel, x) == pytest.approx(net.iz_in4, abs=1e-6)
+    assert section.section_modulus_in3(panel, x) == pytest.approx(net.sz_in3,
+                                                                  abs=1e-6)