Enter Beam Data
Example Data Table
| Input | Example value | Unit | Purpose |
|---|---|---|---|
| Clear span | 6.00 | m | Distance between supports |
| Point load | 12.00 | kN | Concentrated equipment or framing reaction |
| Uniform imposed load | 4.00 | kN/m | Distributed floor or roof load |
| Section modulus | 400.00 | cm³ | Used for bending stress |
| Second moment of area | 8000.00 | cm⁴ | Used for deflection |
Formula Used
The calculator applies static equilibrium to a beam supported at both ends. A point load acts at distance a from the left support. A uniform load acts across the full span L.
wf = (w + self-weight) × load factor
W = Pf + wfL
RB = [Pfa + wfL² / 2] / L
RA = W − RB
V(x) = RA − wfx − PfH(x − a)
M(x) = RAx − wfx² / 2 − Pf(x − a)H(x − a)
σ = Mmax × 10⁶ / Zmm³
The symbol H is zero before the point load and one after it. Deflection is estimated by numerical integration of M/EI while enforcing zero deflection at both simple supports.
How to Use This Calculator
- Enter the clear span between the two supports.
- Enter the point load and its measured distance from the left support.
- Enter full-span uniform load and member self-weight separately.
- Choose a load factor suitable for the check.
- Enter verified section and material properties.
- Select the project deflection limit.
- Calculate and review reactions, shear, moment, stress, and deflection.
- Check bearing, connections, lateral restraint, and code combinations separately.
Simple Beam Load Basics
A simple beam transfers load to supports at both ends. It is common in floor framing, lintels, platforms, and small roof members. The supports allow rotation. They do not carry a fixed-end moment. That behavior makes reaction calculations direct. This calculator combines a single point load with a uniform load. It also includes member self-weight and a chosen load factor. The output helps with early sizing and review.
What The Results Mean
Support reactions show how each end shares vertical load. Shear force describes the internal vertical force at a section. It changes linearly beneath a uniform load. It jumps at a point load. Bending moment describes the turning demand within the beam. Maximum moment is usually the key strength result. A larger section modulus reduces bending stress for the same moment.
Deflection And Serviceability
Strength alone does not guarantee a good beam. Excess deflection can crack finishes, disturb drainage, or create noticeable bounce. The calculator estimates deflection from the bending moment diagram and entered stiffness. Elastic modulus and moment of inertia control stiffness. Use consistent, verified section data. The selected span ratio is a screening limit. Project rules can require different limits. Long spans and low-stiffness members deserve careful attention.
Practical Checks Before Construction
Confirm the support condition before relying on these results. A cantilever, continuous beam, or restrained connection follows different rules. Place point loads at their true locations. Include wall lines, equipment, and concentrated reactions from joists. Add any dead-load allowance required by the design basis. Check load combinations required by the governing code. Review bearing, lateral restraint, connections, shear capacity, and vibration separately. This tool does not replace those checks.
Reading The Load Model
A uniform load is entered per metre of clear span. A point load acts at one chosen distance from the left support. Both loads are multiplied by the selected factor. The program evaluates critical shear and moment locations. It then reports the governing values. Use the calculated reactions when checking posts, bearings, foundations, and connection hardware.
Use Results Responsibly
Input dimensions carefully in the stated units. Compare computed stress with an appropriate allowable or design resistance. Compare calculated deflection with the project limit. A pass in this calculator is not a complete design approval. Material grades, load duration, moisture, fire exposure, and bracing can change capacity. Seek a licensed engineer when safety, permits, public use, or unusual loads are involved.
Frequently Asked Questions
1. What support condition does this calculator model?
It models a simply supported beam. Both ends provide vertical support and allow rotation. It does not model fixed, continuous, cantilever, or partially restrained beams.
2. Can I enter only a uniform load?
Yes. Set the point load to zero. Keep the point-load location within the span because the form still validates the entered position.
3. Can I enter only a point load?
Yes. Set the uniform imposed load and self-weight to zero. Enter the point-load position from the left support accurately.
4. Does the calculator include beam self-weight?
Yes. Enter it as a full-span load in kN/m. It is added to the uniform imposed load before applying the selected load factor.
5. Which load factor should I use?
Use the load combination required by the governing design rules. Use 1.00 for a service-load deflection screening check unless your project requires another basis.
6. Why is the maximum moment not always at midspan?
An off-centre point load shifts the shear-zero position. The maximum moment occurs where shear changes sign or at the point-load location.
7. What section properties are required?
Enter section modulus for the bending stress check. Enter elastic modulus and second moment of area for the deflection estimate. Use verified values for the exact section orientation.
8. Is a passing stress result a complete design?
No. You must also check shear capacity, bearing, web crippling where relevant, lateral restraint, connections, vibration, durability, and local code requirements.
9. Are downward loads the only loads covered?
Yes. The calculator is intended for downward point and full-span uniform loads. Uplift, lateral load, torsion, and partial distributed loads need separate analysis.
10. How accurate is the deflection result?
It uses numerical integration of the elastic bending-moment curve. It is suitable for a preliminary linear-elastic check when inputs and support conditions are correct.
11. When should I seek professional review?
Seek review for permit work, public areas, unusual loading, long spans, damaged members, altered supports, or safety-critical structures. Always confirm final values with a qualified structural engineer.