Failure Load Test of a CFRP Strengthened Railway Bridge in Örnsköldsvik, Sweden
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Abstract
The results obtained when performing a load test to failure of an existing structure are valuable when assessing calculation models, updating finite element models, and investigating the true structural behavior. In this paper a destructive testing and monitoring of a railway bridge in Örnsköldsvik, Sweden is presented. In this particular test the shear capacity of the concrete girders was of primary interest. However, for any reasonable placement of the load (a line load placed transverse to the track direction) a bending failure would occur. This problem was solved by strengthening for flexure using carbon fiber reinforced polymer (CFRP) rectangular rods epoxy bonded in sawed up slots, e.g., near surface mounted reinforcement. The strengthening was very successful and resulted in a desired shear failure when the bridge was loaded to failure. The load-carrying capacity in bending for the unstrengthened and strengthened bridge as well as the shear capacity was predicted with Monte Carlo simulations. The particular calculation presented showed that there was a 25% probability of a bending failure instead of a shear failure. Monitoring showed that the strengthening reduced the strain in the tensile steel reinforcement by approximately 10%, and increased the height of the compressed zone by 100 mm. When the shear failure occurred, the utilization of the compression concrete and CFRP rods were 100 and 87.5%, respectively. This indicates that a bending failure indeed was about to occur, even though the final failure was in shear.
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Acknowledgments
The writers express their gratitude and sincere appreciation to Sustainable Bridges, the Swedish Road Administration, the community of Örnsköldsvik, and Testlab (Laboratory Division at LTU). Ola Enochsson and Arto Puurula are also thanked for their work in the project.
References
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© 2009 ASCE.
History
Received: Apr 18, 2008
Accepted: Oct 13, 2008
Published online: Aug 14, 2009
Published in print: Sep 2009
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