Prestressed CFRP for Strengthening of Reinforced Concrete Structures: Recent Developments at Empa, Switzerland
Publication: Journal of Composites for Construction
Volume 15, Issue 2
Abstract
In civil engineering today, only 20 to 30% of the strength of carbon-fiber-reinforced polymer (CFRP) strips is used when they are applied as externally bonded strips for flexural and shear strengthening or in confinement of reinforced concrete (RC) structural elements. The strips are better used when the CFRP material is prestressed. This offers several advantages, including reduced crack widths, reduced deflections, reduced stress in the internal steel, and possibly increased fatigue resistance. In this paper, recent developments in the field of RC strengthening using prestressed CFRP are presented. The paper focuses on developments in flexural and shear strengthening and column confinement made at the Swiss Federal Laboratory for Materials Testing and Research (Empa). Several innovative ideas have been successfully realized in the laboratory. For example, a gradient prestressing technique without end anchorage plates was developed and successfully applied to a 17 m RC bridge girder. A confinement technique using nonlaminated thermoplastic CFRP straps was also investigated and applied to 2 m high RC columns. These results are encouraging, although practical and theoretical problems remain to be solved before these techniques can be fully applied.
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Acknowledgments
The authors would like to acknowledge the Federal Roads office FEDRO (Astra), the Swiss National Science Foundation SNF and the innovation promotion agency CTI (KTI) for their financial support of some of the presented projects. Furthermore, thanks go to the industrial partners who provided materials or acted as project partners such as Sika, S&P Clever Reinforcement and Carbo-Link, all from Switzerland. Last, the support of the Swiss Federal Laboratories for Materials Testing and Research (Empa) is appreciated.
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Published In
Journal of Composites for Construction
Volume 15 • Issue 2 • April 2011
Pages: 194 - 205
Copyright
© 2011 American Society of Civil Engineers.
History
Received: Sep 29, 2009
Accepted: Mar 19, 2010
Published online: Apr 6, 2010
Published in print: Apr 1, 2011
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