Calculated Results
Results appear here after you calculate, directly below the header.
Ratio uses the larger value of stress demand or deflection demand.
This is a screening check, not a full code design.
Shown for a simply supported beam with combined loading.
Beam Input Form
Bending Moment Diagram
The chart shows the combined moment diagram from uniform load, midspan point load, and self weight.
Formula Used
Cross-sectional area
A = 2(bf × tf) + tw(d - 2tf)
Strong-axis moment of inertia
Ix = 2[(bf × tf³)/12 + (bf × tf)(d/2 - tf/2)²] + [tw(d - 2tf)³]/12
Section modulus
Sx = Ix / (d/2)
Self weight per unit length
wself = A × density × g
Maximum moment
M = (wL²)/8 + (PL)/4 for a simply supported beam.
Maximum shear
V = (wL)/2 + P/2
Bending stress
f = M / Sx
Maximum deflection
Δ = 5wL⁴/(384EI) + PL³/(48EI)
These relations provide a practical preliminary check. Final design should follow your governing steel code, connection design, lateral stability requirements, and load combinations.
How to Use This Calculator
- Select metric or imperial units first so labels stay consistent.
- Enter the W beam geometry: depth, flange width, flange thickness, and web thickness.
- Input span length, distributed load, optional midspan point load, and material properties.
- Set the allowable stress and serviceability deflection ratio for your screening target.
- Press Calculate W Beam to show results above the form.
- Review area, inertia, section modulus, stresses, reactions, deflection, and utilization.
- Use the chart to inspect moment variation across the entire span.
- Export the results to CSV or PDF for documentation and fast comparison.
Example Data Table
| Case | d | bf | tf | tw | Span | UDL | Point Load | E | Stress Limit |
|---|---|---|---|---|---|---|---|---|---|
| Office floor beam | 300 mm | 200 mm | 14 mm | 8 mm | 6.0 m | 18 kN/m | 40 kN | 200000 MPa | 250 MPa |
| Light platform beam | 250 mm | 160 mm | 11 mm | 7 mm | 4.5 m | 10 kN/m | 20 kN | 200000 MPa | 250 MPa |
| Equipment support beam | 400 mm | 200 mm | 16 mm | 10 mm | 7.0 m | 24 kN/m | 70 kN | 200000 MPa | 345 MPa |
FAQs
1. What does this W beam calculator estimate?
It estimates section area, strong-axis inertia, section modulus, self weight, reactions, maximum shear, maximum moment, bending stress, and midspan deflection for a simply supported wide flange beam.
2. What loads can I enter?
This version handles a uniform load across the full span, a single midspan point load, and the beam’s self weight. That combination suits many early sizing checks.
3. Is the calculator suitable for final steel design?
No. It is a preliminary engineering tool. Final design must still check code load combinations, lateral torsional buckling, web bearing, shear capacity, local slenderness, and connection behavior.
4. Why does the result show utilization?
Utilization helps you compare demand against the chosen limit quickly. The tool uses the larger of stress ratio and deflection ratio so you can spot controlling behavior immediately.
5. Which axis does the inertia calculation use?
The calculator uses the major, or strong, bending axis of the W beam. That is usually the axis used for floor beams and common gravity loading checks.
6. Can I use imperial units?
Yes. Switch the unit selector to imperial. The form then interprets dimensions in inches, span in feet, loads in kip-based units, modulus in ksi, and density in pounds per cubic foot.
7. What deflection limit should I use?
Common screening limits are L/240, L/360, and L/480. The right value depends on occupancy, finishes, vibration sensitivity, local code, and project performance requirements.
8. Why is the chart useful?
The moment diagram lets you see where the maximum bending occurs and how load components combine. That helps when comparing alternatives or explaining behavior to clients and teammates.