Masonry · Masonry retaining walls
Reinforced masonry retaining wall calculator
Core-filled blockwork stem on a reinforced concrete base. Rankine active pressure with surcharge; sliding, overturning, eccentricity and bearing of the base; the stem's vertical bars at the base designed by the AS 3700 reinforced-masonry flexure formula, with the masonry shear capacity and the bar spacing.
Standard: AS 4678 stability (sliding, overturning, bearing) · AS 3700-2018 Cl 8.6 reinforced masonry flexure Md = φfsyAsd(1 − 0.6fsyAs/1.3f′m·bd) and shear · Rankine active pressure
Inputs in the worked example
The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.
| Input | Value | Unit |
|---|---|---|
| Retained height (stem) | 2.4 | m |
| Block thickness (core filled) | 290 | mm |
| Toe | 0.6 | m |
| Heel | 1.5 | m |
| Base thickness | 0.35 | m |
| Backfill γ | 19 | kN/m³ |
| Backfill φ′ | 30 | ° |
| Surcharge | 5 | kPa |
| Base friction | 0.5 | |
| Allowable bearing | 150 | kPa |
| Grouted masonry f′m | 8 | MPa |
| fsy | 500 | MPa |
| Bar diameter | 16 | mm |
| Bar spacing (cores) | 200 | mm |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Active thrust (incl. surcharge) | 28.5 | kN/m |
| Sliding FS / overturning FS | 1.79 / 5.19 | |
| Eccentricity (B/6 = 0.40) | 0.040 | m |
| Bearing pressure | 47 | kPa |
| Stem M* at the base | 29.09 | kNm/m |
| Stem steel N16 @ 200 | 1,005 | mm²/m |
| Stem Md | 43.73 | kNm/m |
| Stem V* / Vd | 33.4 / 38.1 | kN/m |
- ✓ Sliding FS ≥ 1.5 — 1.79
- ✓ Overturning FS ≥ 2 — 5.19
- ✓ Resultant in the middle third
- ✓ Bearing ≤ allowable
- ✓ Stem bending M* ≤ Md — 67 %
- ✓ Stem shear
Method, formulas and assumptions
- Rankine Ka with the surcharge as a uniform pressure Ka·q over the full height to the underside of the base.
- Stem (AS 3700 Cl 8.6): Md = φ·fsy·As·d(1 − 0.6fsy·As/(1.3f′m·b·d)), φ = 0.75, d = t/2 for centrally placed bars; shear Vd = φ·f′vm·b·d with f′vm ≈ 0.35 MPa.
- Masonry density 20 kN/m³ (core filled); drainage behind the wall assumed (no water pressure).
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.