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The 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.

Referanser

Meier, U., Deuring, M., Meier, H., Schwegler, G., “Strengthening of structures with CFRP laminates: research and applications in Switzerland”, Proceedings of ACMBS/MCAPC 1st Int.Conference on “Advanced Composite Materials in Bridges and Structures”, Neale, K. W. and Labossière, P. ed., Sherbrooke, Canada, 1992, pp. 243-251.


EN 1194 (1999), “Timber structures - Glued laminated timber - Strength classes and determination of characteristic values”, CEN European Committee for Standardization.


Meier, U and Winistörfer, A., “Multilayer Traction Element in the Form of a Loop”, European Patent 0 815 329, January 7, 1998.


Meier, U., Winistörfer, A.,”Multilayer traction element in the form of a loop”, US-Patent 6’209’279 B1. (2001)


Manduchi, R. and Mian, GA., “Accuracy Analysis for Correlation-Based Image Registration Algorithms”, IEEE International Symposium on Circuits and Systems, ISCAS \'93, 1993, pp. 834-837, ISBN 0-7803-1281-3 1993






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