What is an Ardant truss?
An Ardant truss is a type of roof truss with a curved or parabolic top chord and a straight horizontal bottom chord (tie). The truss is named after the French engineer Paul-Joseph Ardant (1803–1871), who developed it for large spans.
Characteristics
- Curved top chord — the upper edge of the truss follows an arch form (parabolic or circular)
- Horizontal tie — the bottom edge is a straight member that resists the horizontal thrust
- Vertical and diagonal members — connect top and bottom chords and distribute the forces
- Large span — suitable for spans of 15 to 30 metres or more
- Often in timber — originally built in timber, later also in steel
Application
The Ardant truss was and still is used for buildings requiring large, open spaces:
- Riding halls — the original application by Ardant himself
- Churches and chapels — the arched profile suits religious architecture
- Exhibition halls — for large, column-free spaces
- Barns and warehouses — in agriculture for large storage areas
Comparison with other truss types
| Truss type | Key feature |
|---|---|
| Ardant truss | Curved top chord, straight bottom chord |
| King-post truss | Triangular, straight top and bottom chords |
| Polonceau truss | Triangular with tie rods below the truss |
| Arched truss | Fully curved, no horizontal bottom chord |
Related terms
- Truss
- Roof structure
- Purlin
- Span
- Timber frame
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