24x24 High-Strength Column, 8-#10, f'c = 10,000 psi
High-strength concrete column per ACI 318-19 and ACI 318-25: 24x24 / 8-#10 at f'c = 10,000 psi, Grade 60 steel, Pu = 800 kip.
Checked about X: depth h = 24 in
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 | 2,818.00 | 0.00 |
| 2 | Cap intersection | 29.78 | -0.00085 | 0.65 | 2,817.80 | 566.02 |
| 3 | Compression-controlled limit (εt = εty) | 12.64 | 0.00207 | 0.65 | 1,061.77 | 1,003.94 |
| 4 | Transition lower (εt = εty + 0.0015) | 9.76 | 0.00357 | 0.78 | 969.24 | 1,080.31 |
| 5 | Tension-controlled limit (εt = εty + 0.003) | 7.94 | 0.00507 | 0.90 | 900.60 | 1,135.23 |
| 6 | Tension-controlled deep (εt = εty + 0.008) | 4.90 | 0.01007 | 0.90 | 456.16 | 834.94 |
| 7 | Pure bending | 2.49 | 0.02273 | 0.90 | 0.00 | 473.34 |
| 8 | pure_tension | N/A | N/A | 0.90 | -548.64 | 0.00 |
| Quantity | Value |
|---|---|
| Pu (factored axial demand, kip) | 800.00 |
| φPn (axial capacity at operating point, kip) | 2,651.38 |
| Mu (= M2, design moment, kip-ft) | 200.00 |
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) | 662.84 |
| c (neutral axis depth, in) | 28.00 |
| εt (extreme tension strain) | -0.00071 |
| φ (strength reduction factor) | 0.65 |
| φ regime (§21.2.2) | Compression-controlled φ = 0.65 throughout (εt ≤ εty = 0.00207) |
| D/C axial | 0.30 |
| D/C moment | 0.30 |
| kl/r about X | 20.00 |
Nonsway frames only (ACI 318-19 §6.6.4.3). The other axis (about Y) was not checked. kl/r about Y = 20.00 (short-column range). Run about Y |
|
| kl/r limit | 34.00 |
| Tie spacing limit (§25.7.2.1) | 20.32 in (governed by 16·d_bar) |
| Bar clear spacing (§25.2.3) | 4.97 in ≥ 1.91 in |
Force Decomposition at Operating Point (c = 28.00 in, a = 18.20 in)
| Component | Force (kip) | Moment (kip-in) |
|---|---|---|
| Cc (concrete compression) | 3,712.70 | 10,767.74 |
| Cs (steel in compression) | 366.34 | 1,469.37 |
| Ts (steel in tension) | 0.00 | 0.00 |
| Total = Pn, Mn | 4,079.04 | 12,237.12 |
| Layer | Bars | d (in) | εs | fs (ksi) | Force (kip) | Lever (in) | Moment (kip-in) |
|---|---|---|---|---|---|---|---|
| 1 | 4 | 2.63 | 0.00272 | 60.00 | 261.62 | 9.37 | 2,450.07 |
| 2 | 4 | 21.37 | 0.00071 | 20.61 | 104.72 | -9.37 | -980.70 |
| Section geometry | |
| Section | 24 × 24 in (rectangular) |
| Ag (gross area) * | 576.0 in² |
| Ast (total steel area) * | 10.16 in² |
| ρ (reinforcement ratio) * | 0.0176 (1.76%) |
| Materials | |
| f′c | 10,000 psi |
| fy (longitudinal) | 60 ksi (Grade 60) |
| Concrete | Normal weight |
| Reinforcement | |
| Longitudinal bars | 8-#10 |
| Per-face distribution | 2 per b-face, 0 per h-face (+ 4 corners) |
| Clear cover | 1.5 in |
| Transverse | #4 ties @ 12 in |
| Loads | |
| Pu | 800 kip |
| M2 (larger end moment) | 200 kip-ft |
| M1 (smaller end moment) | 0 kip-ft |
| Curvature | Single |
| Bending axis | X |
| Transverse load between supports | No |
| Slenderness parameters | |
| Lu (unsupported length) | 144 in (12.00 ft) |
| k (effective length factor) | 1 |
Assumptions and limits
- Tie arrangement and crossties (§25.7.2.3) are not checked.
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Verdict method 8 · build ded8088 · generated 2026-10-26 10:31 UTC