Calculator Inputs
Metric inputs use kN/m², kN, GPa, and mm⁴.
Load Visualization
This chart compares service area load, service line load, factored line load, shear, and moment. It helps spot dominant demands quickly.
Example Data Table
| Case | Support | Span | Tributary Width | Dead Load | Live Load | Point Load | Self Weight |
|---|---|---|---|---|---|---|---|
| Office floor beam | Simply supported | 6 m | 3 m | 2.5 kN/m² | 3.0 kN/m² | 8 kN | 0.4 kN/m |
| Roof cantilever | Cantilever | 2.5 m | 2 m | 1.8 kN/m² | 0.75 kN/m² | 2 kN | 0.2 kN/m |
| Wood joist check | Simply supported | 14 ft | 1.33 ft | 10 psf | 40 psf | 250 lb | 5 plf |
Formula Used
q = D + L + S + W
w = q × tributary width + member self weight
LRFD style: qu = 1.2D + 1.6L + 0.5 max(S, W)
Uniform load: M = wL² / 8
Center point load: M = PL / 4
Uniform load: M = wL² / 2
Tip point load: M = PL
Simply supported uniform load: Δ = 5wL⁴ / 384EI
Simply supported center point load: Δ = PL³ / 48EI
Cantilever uniform load: Δ = wL⁴ / 8EI
These formulas provide screening-level estimates for common beam cases. Real projects can require code-specific combinations, load paths, lateral effects, vibration checks, stability review, connection design, and professional verification.
How to Use This Calculator
- Select the desired unit system and support type.
- Enter span and tributary width for the member.
- Add dead, live, snow, and wind area loads.
- Enter any extra point load and its location.
- Input member self weight, E, and I values.
- Choose a deflection limit ratio such as L/360.
- Optionally enter allowable moment, shear, and deflection limits.
- Press the calculate button to view loads, reactions, checks, and graph.
- Use the export buttons to save CSV or PDF output.
Frequently Asked Questions
1) What does this structural load calculator estimate?
It estimates service loads, factored loads, support reactions, shear, moment, and deflection for common beam cases. It is useful for quick preliminary checks, comparisons, and educational review before detailed design.
2) Can I use this for steel, wood, or concrete members?
Yes, if you provide suitable stiffness and optional allowable values. The calculator is material-neutral because it works from load, span, modulus of elasticity, and moment of inertia inputs.
3) What is tributary width?
Tributary width is the width of floor, roof, or slab area that transfers load to the member. Area loads multiply by this width to create a line load on the beam.
4) Why are service and factored loads both shown?
Service loads help with deflection and general behavior checks. Factored loads help estimate design demand for strength review. Both are commonly needed during early structural sizing studies.
5) Does the graph replace engineering calculations?
No. The graph helps visualize relative magnitudes only. Final engineering work still needs verified loads, governing building code combinations, member capacity checks, and professional judgment.
6) What deflection limit should I use?
Typical screening values include L/240, L/360, or stricter project-specific limits. The correct value depends on occupancy, finishes, vibration sensitivity, code requirements, and serviceability expectations.
7) Can I include point loads away from the center?
Yes. Switch the point load mode to custom and enter the distance from the left support or fixed end. The calculator then updates reactions, moment, and deflection estimates.
8) Is this enough for permit drawings or construction?
No. Use it for screening and concept work only. Permit and construction documents generally require complete structural analysis, code compliance, detailing, and review by a qualified engineer.