Concrete Design · Reference problem

I-Shaped Special Structural Shear Wall

An spColumn reference example for axial force and bending in an I-shaped reinforced concrete wall.

Open problem in application Download model JSON

Saved model

Problem overview

This case compares the saved RETUG concreteJS wall model with StructurePoint’s spColumn control points. The plot shows the supplied 90° analysis: 100 nominal and factored profiles, including both moment directions. The bundled model includes all 16 published control points as demand checks.

I-shaped special structural wall model preview
The saved I-shaped wall in RETUG concreteJS.
Section
384 × 216 in. overall; 24 in. web and flanges
Geometry
Three rectangular concrete regions forming an I-shaped wall
Reinforcement
156 #8 bars in the saved model
Concrete
f′c = 6 ksi; saved fc6ksi stress–strain curve
Steel
fy = 80 ksi; saved fy80ksi stress–strain curve
Mesh
3 in. edge and interior spacing in the saved model
Units
Dimensions in inches, forces in kip, moments in kip-ft
Saved demand checks
16 published control points; compression uses negative P and Y-moment uses M3

Results

Published vs. computed

100 RETUG profiles · 16 published controls

Factored control points are compared below. Compression is positive on this page; the application uses negative P for compression. Published Y-moment maps to M3 = My for this saved model.

RETUG and spColumn axial force–moment interactionNominal and factored RETUG profiles with spColumn factored control points. Compression is positive; horizontal axis is M3 in kip-ft. The comparison table below provides the control-point values.-600k-400k-200k0k200k400k600k-10k0k20k40k60k80k100kMoment M3 = My (kip-ft)Axial load, P (kip) · compression positiveY: Max. compression · spColumn: P 67,102.0 kip; M3 0.0 kip-ftY: Allowable compression · spColumn: P 53,681.6 kip; M3 195,926.2 kip-ftY: fs = 0 · spColumn: P 41,195.7 kip; M3 352,228.3 kip-ftY: fs = 0.5 fy · spColumn: P 32,476.9 kip; M3 397,760.2 kip-ftY: Balanced point · spColumn: P 27,151.3 kip; M3 407,624.5 kip-ftY: Tension control · spColumn: P 30,250.3 kip; M3 535,871.9 kip-ftY: Pure bending · spColumn: P 0.0 kip; M3 139,631.3 kip-ftY: Max. tension · spColumn: P -8,873.3 kip; M3 0.0 kip-ft−Y: Max. compression · spColumn: P 67,102.0 kip; M3 0.0 kip-ft−Y: Allowable compression · spColumn: P 53,681.6 kip; M3 -195,926.3 kip-ft−Y: fs = 0 · spColumn: P 41,195.7 kip; M3 -352,228.3 kip-ft−Y: fs = 0.5 fy · spColumn: P 32,476.9 kip; M3 -397,760.2 kip-ft−Y: Balanced point · spColumn: P 27,151.3 kip; M3 -407,624.4 kip-ft−Y: Tension control · spColumn: P 30,250.3 kip; M3 -535,871.9 kip-ft−Y: Pure bending · spColumn: P 0.0 kip; M3 -139,630.8 kip-ft−Y: Max. tension · spColumn: P -8,873.3 kip; M3 0.0 kip-ftRETUG profile 0: φP 53,681.6 kip; φM2 0.0 kip-ft; φM3 0.0 kip-ftRETUG profile 1: φP 53,681.6 kip; φM2 0.0 kip-ft; φM3 580.4 kip-ftRETUG profile 2: φP 53,681.6 kip; φM2 0.0 kip-ft; φM3 4,249.9 kip-ftRETUG profile 3: φP 53,681.6 kip; φM2 -0.1 kip-ft; φM3 33,333.3 kip-ftRETUG profile 4: φP 53,681.6 kip; φM2 -0.1 kip-ft; φM3 80,411.7 kip-ftRETUG profile 5: φP 53,681.6 kip; φM2 -0.1 kip-ft; φM3 130,373.3 kip-ftRETUG profile 6: φP 53,681.6 kip; φM2 -0.1 kip-ft; φM3 181,501.5 kip-ftRETUG profile 7: φP 49,859.6 kip; φM2 -0.1 kip-ft; φM3 233,039.2 kip-ftRETUG profile 8: φP 45,637.2 kip; φM2 -0.1 kip-ft; φM3 284,639.5 kip-ftRETUG profile 9: φP 41,323.2 kip; φM2 -0.1 kip-ft; φM3 336,086.9 kip-ftRETUG profile 10: φP 38,553.2 kip; φM2 0.0 kip-ft; φM3 362,796.7 kip-ftRETUG profile 11: φP 36,757.0 kip; φM2 0.0 kip-ft; φM3 374,546.0 kip-ftRETUG profile 12: φP 33,694.1 kip; φM2 0.0 kip-ft; φM3 390,287.6 kip-ftRETUG profile 13: φP 28,662.4 kip; φM2 0.0 kip-ft; φM3 407,809.0 kip-ftRETUG profile 14: φP 29,091.6 kip; φM2 0.0 kip-ft; φM3 454,462.4 kip-ftRETUG profile 15: φP 29,936.0 kip; φM2 0.0 kip-ft; φM3 497,807.9 kip-ftRETUG profile 16: φP 31,034.9 kip; φM2 0.1 kip-ft; φM3 541,077.5 kip-ftRETUG profile 17: φP 27,713.1 kip; φM2 0.2 kip-ft; φM3 517,318.9 kip-ftRETUG profile 18: φP 25,591.0 kip; φM2 0.3 kip-ft; φM3 498,115.6 kip-ftRETUG profile 19: φP 23,042.2 kip; φM2 0.3 kip-ft; φM3 470,720.3 kip-ftRETUG profile 20: φP 19,711.9 kip; φM2 1.0 kip-ft; φM3 427,803.4 kip-ftRETUG profile 21: φP 16,972.9 kip; φM2 -1.5 kip-ft; φM3 389,400.4 kip-ftRETUG profile 22: φP 14,099.2 kip; φM2 -1.5 kip-ft; φM3 348,298.0 kip-ftRETUG profile 23: φP 11,202.3 kip; φM2 -1.8 kip-ft; φM3 306,470.8 kip-ftRETUG profile 24: φP 8,801.5 kip; φM2 -7.8 kip-ft; φM3 271,456.2 kip-ftRETUG profile 25: φP 5,326.0 kip; φM2 -10.1 kip-ft; φM3 220,158.0 kip-ftRETUG profile 26: φP 2,914.0 kip; φM2 -4.4 kip-ft; φM3 184,206.5 kip-ftRETUG profile 27: φP 445.7 kip; φM2 -10.8 kip-ft; φM3 146,520.5 kip-ftRETUG profile 28: φP -1,067.4 kip; φM2 -7.1 kip-ft; φM3 123,194.9 kip-ftRETUG profile 29: φP -3,676.0 kip; φM2 -2.1 kip-ft; φM3 82,466.7 kip-ftRETUG profile 30: φP -5,634.3 kip; φM2 -15.0 kip-ft; φM3 51,499.5 kip-ftRETUG profile 31: φP -5,699.4 kip; φM2 -13.5 kip-ft; φM3 50,467.2 kip-ftRETUG profile 32: φP -5,728.7 kip; φM2 -11.5 kip-ft; φM3 50,002.2 kip-ftRETUG profile 33: φP -5,743.2 kip; φM2 -10.4 kip-ft; φM3 49,771.6 kip-ftRETUG profile 34: φP -5,750.1 kip; φM2 -9.4 kip-ft; φM3 49,662.1 kip-ftRETUG profile 35: φP -5,753.5 kip; φM2 -8.9 kip-ft; φM3 49,607.4 kip-ftRETUG profile 36: φP -5,755.3 kip; φM2 -8.7 kip-ft; φM3 49,580.0 kip-ftRETUG profile 37: φP -5,756.1 kip; φM2 -8.5 kip-ft; φM3 49,566.3 kip-ftRETUG profile 38: φP -5,756.6 kip; φM2 -8.5 kip-ft; φM3 49,559.5 kip-ftRETUG profile 39: φP -5,756.8 kip; φM2 -8.4 kip-ft; φM3 49,556.1 kip-ftRETUG profile 40: φP -5,756.9 kip; φM2 -8.4 kip-ft; φM3 49,554.4 kip-ftRETUG profile 41: φP -5,756.9 kip; φM2 -8.4 kip-ft; φM3 49,553.5 kip-ftRETUG profile 42: φP -5,757.0 kip; φM2 -8.4 kip-ft; φM3 49,553.1 kip-ftRETUG profile 43: φP -5,757.0 kip; φM2 -8.4 kip-ft; φM3 49,552.9 kip-ftRETUG profile 44: φP -5,757.0 kip; φM2 -8.4 kip-ft; φM3 49,552.8 kip-ftRETUG profile 45: φP -5,757.0 kip; φM2 -8.4 kip-ft; φM3 49,552.7 kip-ftRETUG profile 46: φP -5,757.0 kip; φM2 -8.4 kip-ft; φM3 49,552.7 kip-ftRETUG profile 47: φP -5,757.0 kip; φM2 -8.4 kip-ft; φM3 49,552.7 kip-ftRETUG profile 48: φP -5,757.0 kip; φM2 -8.4 kip-ft; φM3 49,552.7 kip-ftRETUG profile 49: φP -5,757.0 kip; φM2 -8.4 kip-ft; φM3 49,552.7 kip-ftRETUG profile 50: φP -8,873.3 kip; φM2 0.0 kip-ft; φM3 0.0 kip-ftRETUG profile 51: φP -5,757.0 kip; φM2 8.4 kip-ft; φM3 -49,552.7 kip-ftRETUG profile 52: φP -5,757.0 kip; φM2 8.4 kip-ft; φM3 -49,552.7 kip-ftRETUG profile 53: φP -5,757.0 kip; φM2 8.4 kip-ft; φM3 -49,552.7 kip-ftRETUG profile 54: φP -5,757.0 kip; φM2 8.4 kip-ft; φM3 -49,552.7 kip-ftRETUG profile 55: φP -5,757.0 kip; φM2 8.4 kip-ft; φM3 -49,552.7 kip-ftRETUG profile 56: φP -5,757.0 kip; φM2 8.4 kip-ft; φM3 -49,552.8 kip-ftRETUG profile 57: φP -5,757.0 kip; φM2 8.4 kip-ft; φM3 -49,552.9 kip-ftRETUG profile 58: φP -5,757.0 kip; φM2 8.4 kip-ft; φM3 -49,553.1 kip-ftRETUG profile 59: φP -5,756.9 kip; φM2 8.4 kip-ft; φM3 -49,553.5 kip-ftRETUG profile 60: φP -5,756.9 kip; φM2 8.4 kip-ft; φM3 -49,554.4 kip-ftRETUG profile 61: φP -5,756.8 kip; φM2 8.4 kip-ft; φM3 -49,556.1 kip-ftRETUG profile 62: φP -5,756.6 kip; φM2 8.5 kip-ft; φM3 -49,559.5 kip-ftRETUG profile 63: φP -5,756.1 kip; φM2 8.5 kip-ft; φM3 -49,566.3 kip-ftRETUG profile 64: φP -5,755.3 kip; φM2 8.7 kip-ft; φM3 -49,580.0 kip-ftRETUG profile 65: φP -5,753.5 kip; φM2 8.9 kip-ft; φM3 -49,607.4 kip-ftRETUG profile 66: φP -5,750.1 kip; φM2 9.4 kip-ft; φM3 -49,662.1 kip-ftRETUG profile 67: φP -5,743.2 kip; φM2 10.4 kip-ft; φM3 -49,771.6 kip-ftRETUG profile 68: φP -5,728.7 kip; φM2 11.5 kip-ft; φM3 -50,002.2 kip-ftRETUG profile 69: φP -5,699.4 kip; φM2 13.5 kip-ft; φM3 -50,467.2 kip-ftRETUG profile 70: φP -5,634.3 kip; φM2 15.0 kip-ft; φM3 -51,499.5 kip-ftRETUG profile 71: φP -3,676.0 kip; φM2 2.1 kip-ft; φM3 -82,466.7 kip-ftRETUG profile 72: φP -1,067.4 kip; φM2 7.1 kip-ft; φM3 -123,194.9 kip-ftRETUG profile 73: φP 445.7 kip; φM2 10.8 kip-ft; φM3 -146,520.5 kip-ftRETUG profile 74: φP 2,914.0 kip; φM2 4.4 kip-ft; φM3 -184,206.5 kip-ftRETUG profile 75: φP 5,326.0 kip; φM2 10.1 kip-ft; φM3 -220,158.0 kip-ftRETUG profile 76: φP 8,801.5 kip; φM2 7.8 kip-ft; φM3 -271,456.2 kip-ftRETUG profile 77: φP 11,202.3 kip; φM2 1.8 kip-ft; φM3 -306,470.8 kip-ftRETUG profile 78: φP 14,099.2 kip; φM2 1.5 kip-ft; φM3 -348,298.0 kip-ftRETUG profile 79: φP 16,972.9 kip; φM2 1.5 kip-ft; φM3 -389,400.4 kip-ftRETUG profile 80: φP 19,711.9 kip; φM2 -1.0 kip-ft; φM3 -427,803.4 kip-ftRETUG profile 81: φP 23,042.2 kip; φM2 -0.3 kip-ft; φM3 -470,720.3 kip-ftRETUG profile 82: φP 25,591.0 kip; φM2 -0.3 kip-ft; φM3 -498,115.6 kip-ftRETUG profile 83: φP 27,713.1 kip; φM2 -0.2 kip-ft; φM3 -517,318.9 kip-ftRETUG profile 84: φP 31,034.9 kip; φM2 -0.1 kip-ft; φM3 -541,077.5 kip-ftRETUG profile 85: φP 29,936.0 kip; φM2 0.0 kip-ft; φM3 -497,807.9 kip-ftRETUG profile 86: φP 29,091.6 kip; φM2 0.0 kip-ft; φM3 -454,462.4 kip-ftRETUG profile 87: φP 28,662.4 kip; φM2 0.0 kip-ft; φM3 -407,809.0 kip-ftRETUG profile 88: φP 33,694.1 kip; φM2 0.0 kip-ft; φM3 -390,287.6 kip-ftRETUG profile 89: φP 36,757.0 kip; φM2 0.0 kip-ft; φM3 -374,546.0 kip-ftRETUG profile 90: φP 38,553.2 kip; φM2 0.0 kip-ft; φM3 -362,796.7 kip-ftRETUG profile 91: φP 41,323.2 kip; φM2 0.1 kip-ft; φM3 -336,086.9 kip-ftRETUG profile 92: φP 45,637.2 kip; φM2 0.1 kip-ft; φM3 -284,639.5 kip-ftRETUG profile 93: φP 49,859.6 kip; φM2 0.1 kip-ft; φM3 -233,039.2 kip-ftRETUG profile 94: φP 53,681.6 kip; φM2 0.1 kip-ft; φM3 -181,501.5 kip-ftRETUG profile 95: φP 53,681.6 kip; φM2 0.1 kip-ft; φM3 -130,373.3 kip-ftRETUG profile 96: φP 53,681.6 kip; φM2 0.1 kip-ft; φM3 -80,411.7 kip-ftRETUG profile 97: φP 53,681.6 kip; φM2 0.1 kip-ft; φM3 -33,333.3 kip-ftRETUG profile 98: φP 53,681.6 kip; φM2 0.0 kip-ft; φM3 -4,249.9 kip-ftRETUG profile 99: φP 53,681.6 kip; φM2 0.0 kip-ft; φM3 -580.4 kip-ft

Hover over a point for its values. Use the legend to show or hide a series.

Download comparison dataDownload plot (SVG)

How points are matched. Named steel-control states; linear interpolation between supplied profiles where needed. Pure bending uses φP = 0; allowable compression uses the published φP and the end of the capped branch. Uniform compression retains the application’s 0.80 axial cap.

spColumn published factored values and RETUG factored values (P in kip; M3 in kip-ft).
PointPublished · spColumnComputed · RETUGDifference (%)
P
kip		M3
kip-ft		P
kip		M3
kip-ft		PM3
Y: Max. compressionProfile 0 · includes 0.80 axial cap 67,102.00.0 53,681.60.0 20.0—
Y: Allowable compressionInterpolated: profiles 6–7 · at published φP 53,681.6195,926.2 53,681.6181,501.7 0.07.4
Y: fs = 0Profile 9 41,195.7352,228.3 41,323.2336,086.9 0.34.6
Y: fs = 0.5 fyInterpolated: profiles 12–13 32,476.9397,760.2 33,529.5390,860.7 3.21.7
Y: Balanced pointProfile 13 27,151.3407,624.5 28,662.4407,809.0 5.60.0
Y: Tension controlProfile 16 30,250.3535,871.9 31,034.9541,077.5 2.61.0
Y: Pure bendingInterpolated: profiles 27–28 0.0139,631.3 0.0139,649.4 —0.0
Y: Max. tensionProfile 50 · uniform tension -8,873.30.0 -8,873.30.0 0.0—
−Y: Max. compressionProfile 0 · includes 0.80 axial cap 67,102.00.0 53,681.60.0 20.0—
−Y: Allowable compressionInterpolated: profiles 94–93 · at published φP 53,681.6-195,926.3 53,681.6-181,501.7 0.07.4
−Y: fs = 0Profile 91 41,195.7-352,228.3 41,323.2-336,086.9 0.34.6
−Y: fs = 0.5 fyInterpolated: profiles 88–87 32,476.9-397,760.2 33,529.5-390,860.7 3.21.7
−Y: Balanced pointProfile 87 27,151.3-407,624.4 28,662.4-407,809.0 5.60.0
−Y: Tension controlProfile 84 30,250.3-535,871.9 31,034.9-541,077.5 2.61.0
−Y: Pure bendingInterpolated: profiles 73–72 0.0-139,630.8 0.0-139,649.4 —0.0
−Y: Max. tensionProfile 50 · uniform tension -8,873.30.0 -8,873.30.0 0.0—

100 × |RETUG − spColumn| / |spColumn|. A dash means the published component is zero, so a relative percentage is undefined. Small differences may round to 0.0%.

Comparison notes

  • P is shown positive in compression to match spColumn. The saved demand cases negate P; M2 = Mx and M3 = My. The 90° curve bends about the model’s Y axis (M3).
  • Orange points are the supplied RETUG factored profiles; the dashed gray line is RETUG nominal strength. The teal line only joins the published control points as a visual guide; it is not a reconstructed spColumn design envelope.
  • The maximum-compression row compares the displayed RETUG value, including its 0.80 axial cap, with spColumn’s uncapped φP maximum. The resulting 20% difference is a capacity-definition difference. spColumn’s allowable-compression row is the corresponding 0.80 limit.
  • Named steel states use the saved curve’s yield strain (0.00207) and the current engine’s tension-control strain (0.00507). The spColumn report uses approximately 0.00276 and 0.00576. These inputs are not identical; the verification does not change them to force agreement.
  • The report notes that the increase in axial capacity between balanced and tension control is omitted from its design diagram. The table compares named states, rather than choosing an arbitrary intersection at the same factored axial load.
  • Small M2 residuals come from the supplied mesh results. Published moments smaller than 0.1 kip-ft are normalized to zero. Values are based on the 3 in. saved mesh and a 100-profile curve; interpolation and displayed rounding are included.