Engineering
Beam Load Calculator
Calculate maximum moment, elastic bending stress, stress utilization, midspan deflection, entered deflection limit, deflection utilization, and residual uniform-load capacity. The dedicated beam diagram shows supports, distributed load, center load, reactions, and separate utilization gauges.
Maximum bending moment (kN m)-
Calculated bending stress (MPa)-
Stress utilization-
Estimated midspan deflection (mm)-
Entered deflection limit (mm)-
Deflection utilization-
Uniform-load capacity after point load (kN/m)-
Decision view
Beam demand versus entered limits
Beam demand versus entered limitsStress and deflection utilizations are kept separate because each has a different physical limit.
Exact scenario comparisonUniform load (kN/m) changes while all other entered assumptions remain constant.
| Uniform load (kN/m) | Maximum bending moment (kN m) | Calculated bending stress (MPa) | Stress utilization | Estimated midspan deflection (mm) | Entered deflection limit (mm) | Deflection utilization | Uniform-load capacity after point load (kN/m) |
|---|
Engineering checks
Load scenarios and demand components
How to use Beam Load Calculator
- Use a consistent service-load basis and include beam self-weight when applicable.
- Enter elastic modulus, second moment of area, and section modulus about the actual bending axis.
- Treat the result as a screening calculation and obtain qualified code review for combinations, stability, shear, vibration, and connections.
Calculator guide
Understanding Beam Load Calculator
A beam can satisfy bending stress and still fail a serviceability limit, or remain stiff while exceeding an allowable stress. This preliminary calculator superimposes a full-span uniform load and a centered point load and keeps the two utilization checks separate.
Calculation method
How the calculation works
Superimpose the simply supported uniform-load and center-point-load moments and deflections, then compare calculated stress and displacement with the entered screening limits. Add wL²/8 and PL/4 for maximum moment, divide moment by section modulus for bending stress, superimpose the standard elastic midspan deflection equations, and compare each demand with its entered limit.
Engineering review
Checks required beyond the calculator
Passing two elastic ratios does not complete a beam design.
Worked situations
Practical examples
- A full-span uniform load creates equal idealized reactions at the two simple supports.
- A centered point load adds one-half of that load to each support reaction.
- Stress utilization and deflection utilization can control independently because section modulus and second moment of area are different properties.
Better inputs
Useful tips
- Check whether loads are characteristic, service, factored, live, dead, or combined before entering them.
- Verify unit conversions for GPa, cm⁴, cm³, metres, kilonewtons, and millimetres.
- Use the correct section orientation and account for holes, notches, composite action, or unbraced length separately.
Before relying on the result
Limitations and common mistakes
- The model assumes a straight prismatic simply supported elastic beam, full-span uniform load, and one centered point load.
- Shear deformation, lateral-torsional buckling, local buckling, bearing, vibration, fatigue, fire, creep, connections, and second-order effects are excluded.
- The entered allowable stress and deflection ratio are user assumptions and are not selected from a building code.
Reference
Key terms
- Section modulus
- Cross-section property used to convert bending moment into extreme-fibre stress.
- Second moment of area
- Cross-section property governing elastic bending stiffness.
- Stress utilization
- Calculated bending stress divided by entered allowable stress.
- Deflection utilization
- Calculated displacement divided by the entered displacement limit.
Important note
Calculated from the entered values using the displayed engineering relationship. Confirm design values, load cases, safety factors, standards, and field conditions with a qualified professional.
Frequently asked questions
Why are there two utilization percentages?
Stress checks strength while deflection checks serviceability; either can govern.
Is self-weight included?
Only if it is added to the entered uniform load.
Can I use a point load away from midspan?
No. This equation assumes the point load is centered.
Does a value below 100% mean the beam is approved?
No. It passes only the two entered screening checks and still requires complete design review.