Steel · Portal frames & crane runways
Crane runway beam (two wheels) calculator
Maximum moment from two moving wheels (Barré position), dynamic factor, lateral surge on the top flange and biaxial check.
Standard: AS 1418.18 / AS 4100 (simplified) · moving load
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 |
|---|---|---|
| Runway span | 7.5 | m |
| Static wheel load | 75 | kN |
| Wheel spacing | 3.2 | m |
| Dynamic factor | 1.15 | |
| Lateral surge (% of wheel load) | 10 | % |
| φMsx of runway beam | 520 | kNm |
| φMsy of top flange | 75 | kNm |
| Ix | 600000000 | mm⁴ |
| Deflection limit span/ | 600 |
Worked example — results
| Result | Value | Unit |
|---|---|---|
| Design wheel load 1.5·φ·P | 129.4 | kN |
| Max moment: P/(2L)(L − a/2)² (two wheels) or PL/4 | 300.2 | kNm |
| Lateral moment (surge, proportional) | 30.02 | kNm |
| Biaxial Mx/φMsx + My/φMsy | 0.978 | |
| Limit | 1.00 | |
| Service deflection (wheels symmetric about midspan) | 9.67 | mm |
| Limit | 12.50 | mm |
- ✓ Biaxial bending
- ✓ Vertical deflection
Method, formulas and assumptions
- Design wheel load 1.5·φ·P = 1.5*1.15*75 = 129.38 kN
- Max moment: P/(2L)(L − a/2)² (two wheels) or PL/4 = IF(3.2<0.586*7.5,129.38/(2*7.5)*(7.5-3.2/2)^2,129.38*7.5/4) = 300.24 kNm
- Lateral moment (surge, proportional) = 300.24*10/100 = 30.024 kNm
- Biaxial Mx/φMsx + My/φMsy = 300.24/520+30.024/75 = 0.97769
- Limit = 1 = 1
- Service deflection (wheels symmetric about midspan) = 75*1.15*1000*((7.5-3.2)/2*1000)*(3*(7.5*1000)^2-4*((7.5-3.2)/2*1000)^2)/(24*200000*6.000e+8) = 9.6749 mm
- Limit = 7.5*1000/600 = 12.5 mm
- Fatigue, wheel-load web crippling and torsion from rail eccentricity are not covered.
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For preliminary design and education. Check every result against the current standard and your own engineering judgement before use.