Beam Input Form
Use this calculator for preliminary steel beam checks. It combines load effects, section properties, stress demand, deflection demand, and export features.
Formula Used
1) Total uniform line load:
wtotal = wapplied + wself
2) Simply supported reactions:
R1 = P(L − a)/L + wL/2
R2 = Pa/L + wL/2
3) Cantilever fixed-end actions:
Vfixed = P + wL
Mfixed = Pa + wL²/2
4) Section force functions:
Shear and moment are calculated across the full beam using statics at many points. This creates the shear diagram, moment diagram, and the peak design actions.
5) Bending stress:
fb = M / Z
6) Required section modulus:
Zreq = Mmax / fallow
7) Deflection check:
Δallow = L / ratio
The calculator numerically integrates curvature, M/EI, to estimate rotation and deflection. That makes the chart practical for different support conditions and combined load cases.
How to Use This Calculator
- Select the support condition: simply supported or cantilever.
- Choose a load case: point load, uniform load, or combined loading.
- Enter the beam span and use the correct length unit.
- Enter the point load and its position, if applicable.
- Enter the uniform load and the beam self weight.
- Enter material stiffness, allowable stress, moment of inertia, and section modulus.
- Choose a deflection ratio such as L/360 or your project requirement.
- Press the calculate button to view reactions, moment, shear, stress, deflection, adequacy checks, exports, and the Plotly graph.
Example Data Table
| Support | Span | Point Load | Point Position | UDL | Self Weight | E | I | Z | Allowable Stress | Deflection Limit |
|---|---|---|---|---|---|---|---|---|---|---|
| Simply Supported | 6.0 m | 20 kN | 3.0 m | 8.0 kN/m | 0.5 kN/m | 200 GPa | 8500 cm⁴ | 850 cm³ | 165 MPa | L/360 |
| Cantilever | 3.5 m | 12 kN | 3.5 m | 3.0 kN/m | 0.35 kN/m | 200 GPa | 6200 cm⁴ | 620 cm³ | 165 MPa | L/180 |
FAQs
1) What does this steel beam load calculator check?
It checks reactions, maximum shear, maximum bending moment, estimated elastic deflection, actual bending stress, required section modulus, and pass or fail status against your entered stress and deflection limits.
2) Can I use it for both simply supported and cantilever beams?
Yes. The form lets you switch between simply supported and cantilever behavior. The program changes the reaction model, internal force equations, and deflection boundary conditions automatically.
3) Does it include beam self weight?
Yes. Beam self weight is entered as a separate line load and added to the applied uniform load. This helps produce a more realistic preliminary service load estimate.
4) Why do I need moment of inertia and section modulus?
Moment of inertia controls stiffness and deflection. Section modulus controls bending stress capacity in this calculator. Both values are needed to judge serviceability and bending adequacy.
5) Is this suitable for final structural design?
No. It is best for planning, checking, and comparing options. Final design should consider code combinations, lateral stability, shear capacity, connection design, local buckling, and engineer review.
6) What deflection ratio should I use?
Common limits include L/240, L/360, and L/480, but project requirements vary. Use the ratio specified by your design code, occupancy type, finish sensitivity, or engineer.
7) Can I export my results?
Yes. After calculation, use the CSV button for spreadsheets or the PDF button for a printable report summary containing the main results from the table.
8) What load units and section units are supported?
The page supports common metric and imperial units for length, force, line load, modulus, inertia, and section modulus. Internally, everything is converted to consistent SI units.