Sample result
Checked about X: depth = 24 in
This is a live sample output for a tied column, bf = 24, tf = 8, bw = 12, hw = 16 in (T-shaped), with 10-#8 longitudinal bars (f′c = 4,000 psi, Grade 60), checked per ACI 318-19 under Pu = 300 kip and M2 = 150 kip-ft. The section is evaluated with the general polygon strain-compatibility model; unlike the rectangular and circular samples it is not checked against a published reference. For background, see the verification pages, the full report (PDF) and the methodology. Run your own column to get an editable .docx calc-note.
Both axial and moment D/C ratios ≤ 1.00.
P-M interaction diagram
Demand (Pu, Mu) tested against the φ-reduced capacity envelope. Operating point (φPn, φMn) shown on the boundary. φ is computed per anchor from εt (§21.2.2); your operating point lies in the compression-controlled region; how the φ transition works.
Interaction Diagram Points (8 anchors, ACI 318-19 Table 22.4.2.1)
| Anchor | Description | c (in) | εt | φ | φPn (kip) | φMn (kip-ft) |
|---|---|---|---|---|---|---|
| 1 | Pure compression cap | N/A | N/A | 0.65 | 911.42 | 0.00 |
| 2 | Cap intersection | 21.37 | 0.00002 | 0.65 | 911.48 | 237.25 |
| 3 | Compression-controlled limit (εt = εty) | 12.72 | 0.00207 | 0.65 | 616.32 | 365.61 |
| 4 | Transition lower (εt = εty + 0.0015) | 9.82 | 0.00357 | 0.78 | 612.77 | 427.86 |
| 5 | Tension-controlled limit (εt = εty + 0.003) | 7.99 | 0.00507 | 0.90 | 558.86 | 469.25 |
| 6 | Tension-controlled deep (εt = εty + 0.008) | 4.94 | 0.01007 | 0.90 | 236.11 | 339.18 |
| 7 | Pure bending | 3.52 | 0.01530 | 0.90 | 0.00 | 227.20 |
| 8 | pure_tension | N/A | N/A | 0.90 | -426.60 | 0.00 |
| Quantity | Value |
|---|---|
| Pu (factored axial demand, kip) | 300.00 |
| φPn (axial capacity at operating point, kip) | 689.44 |
| Mu (= M2, design moment, kip-ft) | 150.00 |
No transverse load between supports. Cm from end-moment ratio per ACI 318-19 §6.6.4.5.3(a). |
|
| φMn (moment capacity, kip-ft) | 344.72 |
| c (neutral axis depth, in) | 14.48 |
| εt (extreme tension strain) | 0.00145 |
| φ (strength reduction factor) | 0.65 |
| φ regime (§21.2.2) | Compression-controlled φ = 0.65 throughout (εt ≤ εty = 0.00207) |
| D/C axial | 0.43 |
| D/C moment | 0.43 |
| kl/r about X | 17.08 |
Nonsway frames only (ACI 318-19 §6.6.4.3). |
|
| kl/r limit | 34.00 |
| Tie spacing limit (§25.7.2.1) | 16.00 in (governed by 16·d_bar) |
| Bar clear spacing (§25.2.3) | 2.00 in ≥ 1.50 in |
| Section geometry | |
| Section | bf = 24, tf = 8, bw = 12, hw = 16 in (T-shaped) |
|
Results assume compression at the marked face of the section drawing; reversed loading may govern and is not checked.
|
|
| Ag (gross area) * | 384.0 in² |
| Ast (total steel area) * | 7.90 in² |
| ρ (reinforcement ratio) * | 0.0206 (2.06%) |
| Materials | |
| f′c | 4,000 psi |
| fy (longitudinal) | 60 ksi (Grade 60) |
| Concrete | Normal weight |
| Reinforcement | |
| Longitudinal bars | 10-#8 |
| Bar distribution | 10 bars around the perimeter (one at each corner, the rest spaced along the edges) |
| Clear cover | 1.5 in |
| Transverse | #4 ties @ 12 in |
| Loads | |
| Pu | 300 kip |
| M2 (larger end moment) | 150 kip-ft |
| M1 (smaller end moment) | 0 kip-ft |
| Curvature | Single |
| Bending axis | X |
| Transverse load between supports | No |
| Slenderness parameters | |
| Lu (unsupported length) | 120 in (10.00 ft) |
| k (effective length factor) | 1 |
Section diagram
(bending about X)Assumptions and limits
- Tie arrangement and crossties (§25.7.2.3) are not checked.
- Results assume compression at the marked face of the section drawing; reversed loading may govern and is not checked.
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Verdict method 9 · build 8c8c828 · generated 2026-10-28 01:53 UTC