FlexiArch: A flexible precast concrete arch

Arches have been used in construction for over 2000 years, as they are strong and exceptionally durable.  However their use is less frequent in modern construction, as construction is difficult and time consuming, as temporary formwork is needed to support the arch until it is fully constructed.  FlexiArch is a “flat pack” precast concrete solution, that allows durable arched bridges to be constructed quickly and easily, that was conceived by staff and students at Queen’s in the late 1990s.  The concept was patented in the early 2000s, and in collaboration with Macrete Ireland, the first FlexiArch bridge was installed near Belfast in September 2007. 

Sustainability is a key aspect of the FlexiArch design.  As FlexiArch contains no reinforcement (the main cause of deterioration of modern reinforced concrete structures), it is an extremely durable when properly maintained.  FlexiArch is quick and easy to install, reducing any disruption to local communities.  It also is transported as a flat beam, reducing transportation costs. 

The image below show a typical Installation sequence:

1. An entire arch arrives flat packed on a single lorry.  Each 1m wide FlexiArch unit is by a single crane, making it ideal for restrictive sites.  As the FlexiARch unit is lifted, it centres under it’s own weight. 
2. The FlexiArch unit is then placed on cast in-situ tapered footings.
3. A number if 1m wide FlexiArch units are placed side by side to form a bridge of any width.  Due to the ease of installation it is possible to install a whole arch in less than a day.
4. The completed FlexiArch is backfilled with lean mix concrete and can be faced with precast concrete panels or brick.

For further information, please contact:

Prof Adrian Long
Centre for Built Environment Research (CBER)
School of Planning, Architecture and Civil Engineering
Tel: +44 (0(28 9097 4005
E-Mail: a.long@qub.ac.uk

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