Design, construction and monitoring of a bowstring arch bridge made exclusively of timber, CFRP and
|Forfattere||Rolf Brönnimann, Robert Widmann|
|Nøkkelord||Bowstring Bridge, Timber, Glulam GFRP, CFRP, Monitoring|
|Utgiver||Tapir Akademisk Forlag|
|Adresse utgiver||Tapir Akademisk Forlag Besøksadresse: Nardoveien 12 Postadresse: Postboks 2461 Sluppen 7005 Trondheim|
AbstraktThe replacement of an existing pedestrian bridge at the Swiss Federal Laboratories for Materials Testing and Research, Empa, Switzerland, was an opportunity to apply a novel and experimental bridge design. The decision was to build a bowstring arch bridge. A remarkable feature of the design is the exclusive use of non-metallic construction materials, namely timber, carbon fiber reinforced plastics CFRP and glass fiber reinforced plastics GFRP. The span of the bridge is 12.0 m and the cross section of the timber bridge deck is 3.0 m by 0.16 m. The wooden deck is prestressed laterally and longitudinally (the bowstring) by CFRP loops. The lateral prestressing aims at enhancing dimensional stability of the deck while the longitudinal CFRP loops act as a bowstring of the arch and thus shape and stiffen the construction.
The bridge was preassembled and tested under load indoors in order to obtain stiffness properties and data about the tension stresses within the CFRP loops. After having been transported to the site it was lifted into place by a crane.
Since its installation in March 2007 the stability of the bridge has been continuously monitored. Several specific sensors are used to record deformations, bowstring tension, temperature and humidity. Among the sensors are a special load cell for measuring the bowstring tension and a video surveillance of specially designed optical targets underneath the bridge deck for deformation measurements.
This paper will highlight key design features as well as important steps of the production and installation process of the bridge. The most significant results of the load tests and the monitoring phase will be reported.
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