Masonry · Walls in compression
Unreinforced masonry wall: compression calculator
Characteristic masonry strength from the unit strength, slenderness Srs and reduction ks, design compressive capacity per metre.
Standard: AS 3700 Cl 3.3, 7.3 (simplified)
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 |
|---|---|---|
| Unit compressive strength f′uc | 20 | MPa |
| Mortar factor km | 1.4 concrete units / M3 | |
| Wall thickness | 190 | mm |
| Height | 2.7 | m |
| Vertical restraint av | 1.0 laterally supported top & bottom | |
| Thickness coefficient kt | 1 | |
| Design load | 180 | kN/m |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| f′m = km √f′uc | 6.26 | MPa |
| Srs = av H/(kt t) | 14.21 | |
| ks = 1.18 − 0.03 Srs (≤ 1) | 0.754 | |
| φFo = 0.75 f′m Ab | 892.2 | kN/m |
| kFo | 672.4 | kN/m |
- ✓ N* ≤ k φFo
- ✓ Srs ≤ 27
Method, formulas and assumptions
- f′m = km √f′uc = 1.4*SQRT(20) = 6.261 MPa
- Srs = av H/(kt t) = 1*2.7*1000/(1*190) = 14.211
- ks = 1.18 − 0.03 Srs (≤ 1) = MIN(1,MAX(0,1.18-0.03*14.211)) = 0.75368
- φFo = 0.75 f′m Ab = 0.75*6.261*190 = 892.19 kN/m
- kFo = 0.75368*892.19 = 672.43 kN/m
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.