An arched truss is a structural element that combines the curved form of an arch with the lightweight, rigid framework of a truss to span large distances without intermediate supports. It is widely used in sports halls, exhibition centers, aircraft hangars, warehouses, and agricultural buildings where column-free interior space is required.
Application
Arched trusses offer an efficient solution for covering wide spans while keeping material use and self-weight to a minimum. Their design and use encompass the following aspects:
- Structural principle: The arched shape directs loads primarily into compression along the curve, while the truss web members (diagonals and verticals) handle shear forces and provide stability against buckling. This combination allows spans of 30 meters or more with relatively slender members.
- Materials: Arched trusses are manufactured in steel, glued-laminated timber (glulam), or a combination of both. Timber arched trusses are popular for their aesthetic warmth and sustainability credentials.
- Two-hinged and three-hinged arches: A two-hinged arched truss has pin connections at the supports; a three-hinged version adds a pin at the crown. The three-hinged variant is statically determinate, simplifying analysis and accommodating thermal movement.
- Roof cladding support: Purlins span between adjacent arched trusses, supporting the roof cladding (metal sheeting, membrane, or glazing). The spacing between trusses typically ranges from 4 to 8 meters.
- Transportation and erection: Large arched trusses are often fabricated in sections and assembled on site. They may be lifted into place by crane in one piece or erected in halves that are connected at the crown.
- Portal frame alternative: For moderate spans (15-30 meters), arched trusses compete with portal frames, offering a more open interior profile and reduced horizontal thrust on foundations.
The curved profile also provides natural drainage for rainwater and snow, reducing ponding loads on the roof surface.
Related terms
- Portal frame
- Glulam beam
- Lattice girder
- Tied arch
- Purlin
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