Formula used
Support coefficients vary by the selected boundary condition. Point loads use conservative superposition. Final design checks require project-specific standards and verified profile data.
How to use
- Choose the support and analysis method.
- Enter span and tributary widths.
- Add positive and negative wind pressures.
- Enter section and material properties.
- Add reinforcement, point loads, and thermal criteria.
- Review strength, deflection, reactions, and movement clearance.
- Export the report for engineering review.
Example data
| Input | Example | Purpose |
|---|---|---|
| Span | 3.6 m | Unsupported mullion length |
| Tributary width | 1.5 m | Total supported façade width |
| Wind pressure | +1.5 / −1.8 kPa | Inward and outward pressure |
| Elastic modulus | 69,000 MPa | Aluminium stiffness |
| Moment of inertia | 2,500,000 mm⁴ | Mullion flexural stiffness |
| Section modulus | 35,000 mm³ | Bending stress resistance |
| Deflection limit | L/175 and 15 mm | Governing serviceability limit |
Frequently asked questions
What does tributary width mean?
It is the façade width transferring pressure into one mullion.
Should positive and negative pressures be checked?
Yes. Wind suction often governs mullion bending and anchor reactions.
Which deflection limit should be used?
Use the project specification and applicable façade design standard.
Can steel reinforcement be included?
Yes. Enter reinforcement area, inertia, modulus, centroid, and effectiveness.
Does this calculator design anchors?
It reports reactions. Detailed anchor and connection design remains separate.
Are continuous mullions calculated exactly?
The page uses practical coefficient methods for preliminary comparison.
Can point loads be added?
Yes. Enter each load as magnitude@position within the span.
Why calculate thermal movement?
Mullions need sufficient splice and perimeter movement clearance.
Is a passing result final approval?
No. A qualified façade or structural engineer must verify design.
Important limitations
This tool supports preliminary mullion sizing and comparison. It does not replace sealed engineering calculations. Verify local buckling, torsion, splices, anchors, glass edges, and standards.