Rebar tables
Bar areas, diameters and weights, area per foot (per metre) for every bar at the usual spacings, the bars that give a required area, and quick development, lap splice and standard hook lengths per ACI 318-19 25.4 and 25.5 for the concrete and bar detail you describe. For a full development or splice calculation with every factor, use the Rebar development calculation.
Inputs of the rebar tables #
- Bar, spacing s, required area per foot (checked: the area provided must reach it) and required total area (the tables list how many bars of each size give it).
- Materials: f'c, reinforcement grade (ψg of Table 25.4.2.5: 1.0 for Grade 60, 1.15 for Grade 80), concrete type and density (λ, Table 19.2.4.1).
- Development length: Table 25.4.2.3, the simplified expressions, with spacing and cover condition met your judgment of the detail (clear spacing and cover at least db with the minimum stirrups or ties along ℓd, or clear spacing at least 2db with cover at least db); or Eq. 25.4.2.4a with the confinement term (cb + Ktr)/db you enter (at most 2.5; 1.5 prefilled; Ktr = 0 is permitted).
- Top bar (ψt = 1.3), epoxy coating (ψe = 1.5 or 1.2; ψt ψe ≤ 1.7).
- Lap splice class: Class B (1.3 ℓd), or Class A (1.0 ℓd) where the area provided is at least twice that required over the lap and at most half the bars are spliced there.
- Hooks: ψr (1.0 with enough confining ties, else 1.6) and ψo (1.0 inside a column core with side cover ≥ 2.5 in., or side cover ≥ 6db; else 1.25), Table 25.4.3.2.
- Length available for the straight bar beyond the critical section.
There is no auto-design: these are reference tables for the bar you choose.
Checks performed #
| Check | Basis |
|---|---|
| Area per foot provided | Ab × 12 / s (Ab × 1000 / s per metre) against the required area |
| Bars for the required total area | n = As,req / Ab, rounded up |
| Development length of a straight bar | ACI 318-19 Table 25.4.2.3 or Eq. 25.4.2.4a, √f'c ≤ 100 psi (25.4.1.4), ℓd ≥ 12 in. (25.4.2.1); against the length available |
| Tension lap splice | 25.5.2.1: max(1.3 ℓd or 1.0 ℓd, 12 in.); #14 and #18 bars are not lap spliced in tension (25.5.1.1) |
| Standard hook | 25.4.3.1: ℓdh = (fy ψe ψr ψo ψc / (55 λ √f'c)) db^1.5 ≥ max(8db, 6 in.) |
The report prints the area table for every bar and spacing and the development, lap and hook lengths for every bar.
Limitations #
- Deformed bars in tension. Compression development (25.4.9), headed bars (25.4.4), bundled bars (25.6), excess reinforcement (25.4.10), welded wire reinforcement and seismic provisions of Chapter 18 are not covered.
- Hook detail (bend diameter, tail) is not drawn or checked.
- Weights are the ASTM A615 Table 1 nominal weights.
Verification examples #
Verification status: 9 values compared in 8 examples (8 published, 0 hand calculations from the cited equations): 9 within tolerance, 0 recorded deviations. Code basis: the provisions it uses were read in the target edition.
Hand values of the ACI 318-19 expressions for f'c = 4000 psi, Grade 60, normalweight, uncoated (tests/test_verify_rebar_tables.py):
| Example | Case | Hand value | ILX Calcs |
|---|---|---|---|
| RT-A1, -A2 | #5 at 12 in.; #4 at 6 in. | 0.31; 0.40 in²/ft | same |
| RT-D1 | #5, condition met | ℓd = 23.72 in.; Class B lap 30.84 in. | same |
| RT-D2, -D3 | #8, condition met; other cases | 47.43; 71.15 in. | same |
| RT-D4 | #6 top bar, condition met | 37.00 in. | same |
| RT-D5 | #5, Eq. 25.4.2.4a, (cb + Ktr)/db = 2.5 | 14.23 in. | same |
| RT-H1 | #5 standard hook, ψr = 1.6, ψo = 1.25 | 14.77 in. | same |