Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical Modeling
This paper presents a study on the load carrying capacity of reinforced concrete (RC) beams strengthened with externally bonded (EB) carbon fiber reinforced polymer (CFRP) strips prestressed up to 0.6% in strain. At the strip ends, the innovative gradient anchorage is used instead of conventional me...
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doaj-f842bc25e4ab4869af0ba02ca4c36a2b2020-11-25T02:25:21ZengMDPI AGPolymers2073-43602014-01-016111413110.3390/polym6010114polym6010114Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical ModelingJulien Michels0Enzo Martinelli1Christoph Czaderski2Masoud Motavalli3Structural Engineering Research Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf 8600, SwitzerlandDepartment of Civil Engineering, University of Salerno, via Giovanni Paolo II 132, Fisciano 84084, ItalyStructural Engineering Research Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf 8600, SwitzerlandStructural Engineering Research Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, Dübendorf 8600, SwitzerlandThis paper presents a study on the load carrying capacity of reinforced concrete (RC) beams strengthened with externally bonded (EB) carbon fiber reinforced polymer (CFRP) strips prestressed up to 0.6% in strain. At the strip ends, the innovative gradient anchorage is used instead of conventional mechanical fasteners. This method, based on the epoxy resin’s ability to rapidly cure under high temperatures, foresees a sector-wise heating followed by a gradual decrease of the initial prestress force towards the strip ends. The experimental investigation shows a promising structural behavior, resulting in high strip tensile strains, eventually almost reaching tensile failure of the composite strip. Additionally, ductility when considering deflection at steel yielding and at ultimate load is satisfying, too. From a practical point of view, it is demonstrated that premature strip grinding in the anchorage zone is not beneficial. In addition, a non-commercial 1D finite element code has been enlarged to an EB reinforcement with prestressed composite strips. A bilinear bond stress-slip relation obtained in earlier investigations is introduced as an additional failure criterion to the code. The numerical code is able to almost perfectly predict the overall structural behavior. Furthermore, the calculations are used for comparison purposes between an initially unstressed and a prestressed externally bonded composite reinforcement. The increase in cracking and yielding load, as well as differences in structural stiffness are apparent.http://www.mdpi.com/2073-4360/6/1/114CFRPstructural retrofittingexternally bonded reinforcementprestressinggradient anchorageexperimental investigationfinite element model |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Julien Michels Enzo Martinelli Christoph Czaderski Masoud Motavalli |
spellingShingle |
Julien Michels Enzo Martinelli Christoph Czaderski Masoud Motavalli Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical Modeling Polymers CFRP structural retrofitting externally bonded reinforcement prestressing gradient anchorage experimental investigation finite element model |
author_facet |
Julien Michels Enzo Martinelli Christoph Czaderski Masoud Motavalli |
author_sort |
Julien Michels |
title |
Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical Modeling |
title_short |
Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical Modeling |
title_full |
Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical Modeling |
title_fullStr |
Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical Modeling |
title_full_unstemmed |
Prestressed CFRP Strips with Gradient Anchorage for Structural Concrete Retrofitting: Experiments and Numerical Modeling |
title_sort |
prestressed cfrp strips with gradient anchorage for structural concrete retrofitting: experiments and numerical modeling |
publisher |
MDPI AG |
series |
Polymers |
issn |
2073-4360 |
publishDate |
2014-01-01 |
description |
This paper presents a study on the load carrying capacity of reinforced concrete (RC) beams strengthened with externally bonded (EB) carbon fiber reinforced polymer (CFRP) strips prestressed up to 0.6% in strain. At the strip ends, the innovative gradient anchorage is used instead of conventional mechanical fasteners. This method, based on the epoxy resin’s ability to rapidly cure under high temperatures, foresees a sector-wise heating followed by a gradual decrease of the initial prestress force towards the strip ends. The experimental investigation shows a promising structural behavior, resulting in high strip tensile strains, eventually almost reaching tensile failure of the composite strip. Additionally, ductility when considering deflection at steel yielding and at ultimate load is satisfying, too. From a practical point of view, it is demonstrated that premature strip grinding in the anchorage zone is not beneficial. In addition, a non-commercial 1D finite element code has been enlarged to an EB reinforcement with prestressed composite strips. A bilinear bond stress-slip relation obtained in earlier investigations is introduced as an additional failure criterion to the code. The numerical code is able to almost perfectly predict the overall structural behavior. Furthermore, the calculations are used for comparison purposes between an initially unstressed and a prestressed externally bonded composite reinforcement. The increase in cracking and yielding load, as well as differences in structural stiffness are apparent. |
topic |
CFRP structural retrofitting externally bonded reinforcement prestressing gradient anchorage experimental investigation finite element model |
url |
http://www.mdpi.com/2073-4360/6/1/114 |
work_keys_str_mv |
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