The Gradient Anchorage Method for Prestressed CFRP Strips: from the Development to the Strengthening of an 18 M Long Bridge Girder

Breveglieri, Matteo; Czaderski, Christoph; Michels, Julien

doi:10.2478/sjce-2018-0018

Abstract

The external bonding of carbon fiber-reinforced polymer (CFRP) strips by two-component epoxy adhesive on the concrete surfaces of buildings and bridges is a retrofitting method accepted worldwide. The gradient anchorage (GA) is an anchoring method especially developed to anchor prestressed CFRP strips to concrete elements without a need for mechanical clamping after the installation phase. This method takes advantage of the adhesives property to undergo accelerated curing when heated. The results of more than fifteen years of research on the development of the gradient anchorage at the Swiss Federal Laboratories for Materials Science and Technology (Empa) are presented in this paper. The basic principles and application steps are explained, and the main results starting from the development of the technique up to the testing of real scale girders are described, and the new challenges posed by this innovative system are highlighted. The gradient anchorage is a valid alternative to a mechanically anchored system for prestressed FRP (P-FRP).

References

Aram M. R. - Czaderski C. - Motavalli, M. (2008)Effects of gradually anchored prestressed CFRP strips bonded on prestressed concrete beams. J. Compos. Constr. 12 (1), 25-34. https://doi.org/10.1061/(ASCE)1090-0268(2008)12:1(25)).10.1061/(ASCE)1090-0268(2008)12:1(25))
Open DOI Search in Google Scholar Back to article
Czaderski C. - Motavalli M. (2007)40-Year-old full-scale concrete bridge girder strengthened with prestressed CFRP plates anchored using gradient method. Composites B. 38 (7-8), 878-886. https://doi.org/10.1016/j.compositesb.2006.11.003.10.1016/j.compositesb.2006.11.003
Open DOI Search in Google Scholar Back to article
Czaderski, C. (2012)Strengthening of reinforced concrete members by prestressed, externally bonded reinforcement with gradient anchorage. Doctoral dissertation, ETH Zürich: Switzerland, 458 p. https://doi.org/10.3929/ethz-a-007569614.10.3929/ethz-a-007569614
Open DOI Search in Google Scholar Back to article
Czaderski C. - Martinelli E. - Michels J. - Motavalli M. (2012)Effect of curing conditions on strength development in an epoxy resin for structural strengthening. Composites B, 43 (2), 398-410. https://doi.org/10.1016/j.compositesb.2011.07.006.10.1016/j.compositesb.2011.07.006
Open DOI Search in Google Scholar Back to article
Czaderski C. - Gallego J. M. - Michels J. (2017)Temperature stability and durability of Externally Bonded CFRP strips in bridge construction. (Forschung im Strassenwesen No. 684). Bern: Eidgenössisches Departement für Umwelt, Verkehr, Energie und Kommunikation UVEK, Bundesamt für Strassen ASTRA.
Search in Google Scholar Back to article
Czaderski, C. - Meier, U. (2018)EBR strengthening technique for concrete, long-term behaviour and historical survey. Polymers, 10 (1), 77; https://doi.org/10.3390/polym10010077.10.3390/polym10010077641494630966121
Open DOI Search in Google Scholar Back to article
Correia L. - Teixeira T. – Michels J. - Almeida J. A. P. P. - Sena-Cruz J. (2015)Flexural behaviour of RC slabs strengthened with prestressed CFRP strips using different anchorage systems. Composites B 2015, 81, 158-170. https://doi.org/10.1016/j.compositesb.2015.07.011.10.1016/j.compositesb.2015.07.011
Open DOI Search in Google Scholar Back to article
Correia L. - Sena-Cruz J. - Michels J. – França P. – Pereira E. – Escusa G. (2017)Durability of RC slabs strengthened with prestressed CFRP laminate strips under different environmental and loading conditions. Composites B 2017, 125, 71-88. https://doi.org/10.1016/j.compositesb.2017.05.047.10.1016/j.compositesb.2017.05.047
Open DOI Search in Google Scholar Back to article
Deuring, M. (1993)Verstärken von Stahlbeton mit gespannten Faserverbundwerkstoffen; Empa-Berichte, Vol. 224; Empa: Dübendorf; 279 pp.
Search in Google Scholar Back to article
Gallego J. M. - Czaderski C. - Michels J. (2016)Prestress force-release tests at elevated temperatures - Gradient anchorage stability for prestressed EB CFRP strips. Compos. Struct., 137, 159-169. https://doi.org/10.1016/j.compstruct.2015.11.022.10.1016/j.compstruct.2015.11.022
Open DOI Search in Google Scholar Back to article
Gallego J. M. - Michels J. - Czaderski C. (2017)Influence of the asphalt pavement on the short-term static strength and longterm behaviour of RC slabs strengthened with externally bonded CFRP strips. Eng. Struct. 150, 481-496. https://doi.org/10.1016/j.engstruct.2017.07.063.10.1016/j.engstruct.2017.07.063
Open DOI Search in Google Scholar Back to article
Gallego, J. M. - Czaderski, C. - Breveglieri, M. – Michels, J. (2018)Fatigue behaviour at elevated temperature of RC slabs strengthened with EB CFRP strips. Composites B, 141, 37-49. https://doi.org/10.1016/j.compositesb.12.026.10.1016/j.compositesb.12.026
Open DOI Search in Google Scholar Back to article
Harmanci Y. E. - Michels J. - Czaderski C. - Motavalli M. (2016)Calculation technique for externally unbonded CFRP strips in structural concrete retrofitting. J. Eng. Mech. 142 (6), 04016026 (12 pp.). https://doi.org/10.1061/(ASCE)EM.1943-7889.000101410.1061/(ASCE)EM.1943-7889.0001014
Open DOI Search in Google Scholar Back to article
Harmanci Y. E. - Michels J. - Czaderski C. – Loser R. – Chatzi E. (2018a)Long-term residual anchorage resistance of gradient anchorages for prestressed CFRP strips. Composites B, 139, 171-184. https://doi.org/10.1016/j.compositesb.2017.11.062.10.1016/j.compositesb.2017.11.062
Open DOI Search in Google Scholar Back to article
Harmanci Y. E. - Michels J. - Chatzi E. (2018b)Behaviour of Prestressed CFRP Anchorages during and after Freeze-Thaw Cycle Exposure. Polymers, 10 (6), 565; https://doi.org/10.3390/polym10060565.10.3390/polym10060565
Open DOI Search in Google Scholar Back to article
Kim, Y. J. - Wight R. G. - Green, M. F. (2008)Flexural strengthening of RC beams with prestressed CFRP sheets: Development of nonmetallic anchor systems. J. Compos. Constr., 12(1), 35–43. https://doi.org/10.1061/(ASCE)1090-0268(2008)12:1(35).10.1061/(ASCE)1090-0268(2008)12:1(35)
Open DOI Search in Google Scholar Back to article
Kotynia R. - Walendziak R. - Stoecklin I. - Meier U. (2011)RC slabs strengthened with prestressed and gradually anchored CFRP strips under monotonic and cyclic loading. J. Compos. Constr. 2011, 15 (2), 168-180. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000081.10.1061/(ASCE)CC.1943-5614.0000081
Open DOI Search in Google Scholar Back to article
Kotynia R. - Staskiewicz M. - Michels J. - Czaderski C. - Motavalli M. (2015)Pioneering strengthening of bridge girders with pretensioned CFRP laminates in Poland. Presented at the Third Conference on Smart Monitoring, Assessment and Rehabilitation of Structures (SMAR 2015), Antalya, Turkey, 7-9 September 2015; Itü; Empa, 2015; 8 pp.
Search in Google Scholar Back to article
Matsui K. (1990)Effects of curing conditions and test temperatures on the strength of adhesive-bonded joints. Int J Adhes Adhes;10(4):277–84. https://doi.org/10.1016/0143-7496(90)90046-Z10.1016/0143-7496(90)90046-Z
Open DOI Search in Google Scholar Back to article
Meier U. - Stöcklin, I (2005)A novel carbon fiber reinforced polymer (CFRP) system for post-strengthening. In International Conference on Concrete Repair, Rehabilitation and Retrofitting (ICCRRR), Taylor & Francis Group, London, 477–479.
Search in Google Scholar Back to article
Meier U. (2007) Is there a future for automated application of CFRP strips for post-strengthening? Presented at the 8th International Symposium on Fiber-Reinforced Polymer Reinforcement for Concrete Structures (FRPRCS-8), Patras, Greece, July 16-18, 2007; 10 pp.
Search in Google Scholar Back to article
Michels J. – Czaderski C - El-Hacha R. – Brönnimann R. – Motavalli M. (2012)Temporary bond strength of partly cured epoxy adhesive for anchoring prestressed CFRP strips on concrete. Compos. Struct. 2012, 94 (9), 2667-2676. https://doi.org/10.1016/j.compstruct.2012.03.037.10.1016/j.compstruct.2012.03.037
Open DOI Search in Google Scholar Back to article
Michels J. - Sena-Cruz J. - Czaderski C. - Motavalli M. (2013)Structural strengthening with prestressed CFRP strips with gradient anchorage. J. Compos. Constr. 2013, 17 (5), 651-661. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000372.10.1061/(ASCE)CC.1943-5614.0000372
Open DOI Search in Google Scholar Back to article
Michels J. - Zile E. - Czaderski C. - Motavalli, M. (2014)Debonding failure mechanisms in prestressed CFRP/epoxy/concrete connections. Eng. Fract. Mech. 2014, 132, 16-37. https://doi.org/10.1016/j.engfracmech.2014.10.012.10.1016/j.engfracmech.2014.10.012
Open DOI Search in Google Scholar Back to article
Michels J. - Widmann R. - Czaderski C. - Allahvirdizadeh R. – Motavalli M. (2015)Glass transition evaluation of commercially available epoxy resins used for civil engineering applications. Composites B, 77, 484-493. https://doi.org/10.1016/j.compositesb.2015.03.053.10.1016/j.compositesb.2015.03.053
Open DOI Search in Google Scholar Back to article
Michels J. - Barros J. - Costa, I. – Sena-Cruz J. - Czaderski C. - Giacomin G. - Kotynia R. - Lees J. – Pellegrino C. – Zile E. (2016a)Prestressed FRP Systems. In Design Procedures for the Use of Composites in Strengthening of Reinforced Concrete Structures, Pellegrino, C., Sena-Cruz, J., Eds.; RILEM state-of-the-art reports, Vol. 19; Springer, 2016; pp. 263-301. https://doi.org/10.1007/978-94-017-7336-2_7.10.1007/978-94-017-7336-2_7
Open DOI Search in Google Scholar Back to article
Michels J. – Sena-Cruz, J. - Christen R. - Czaderski C. - Motavalli, M. (2016b)Mechanical performance of cold-curing epoxy adhesives after different mixing and curing procedures. Composites B, 98, 434-443. https://doi.org/10.1016/j.compositesb.2016.05.054.10.1016/j.compositesb.2016.05.054
Open DOI Search in Google Scholar Back to article
Michels J. - Staśkiewicz M. - Czaderski C. – Kotynia R. - Harmanci Y. E. - Motavalli M. (2016c)Prestressed CFRP strips for concrete bridge girder retrofitting: application and static loading test. J. Bridge Eng. 2016, 21 (5), 04016003 (14 pp.). https://doi.org/10.1061/(ASCE)BE.1943-5592.0000835.10.1061/(ASCE)BE.1943-5592.0000835
Open DOI Search in Google Scholar Back to article
Mohee F. M. - Al-Mayah A. - Plumtree A. (2016)Anchors for CFRP plates: State-of-the-art review and future potential. Composites B, 90, 432-442. https://doi.org/10.1016/j.compositesb.2016.01.011.10.1016/j.compositesb.2016.01.011
Open DOI Search in Google Scholar Back to article
Motavalli M. - Czaderski C. - Pfyl-Lang K. (2011)Prestressed CFRP for strengthening of reinforced concrete structures: recent developments at Empa, Switzerland. J. Compos. Constr., 15 (2), 194-205. https://doi.org/10.1061/(ASCE)CC.1943-5614.0000125.10.1061/(ASCE)CC.1943-5614.0000125
Open DOI Search in Google Scholar Back to article
Silva P. – Fernandes P. - Sena-Cruz J. - Xavier J. - Castro F. - Soares D. – Carneiro V. (2016)Effects of different environmental conditions on the mechanical characteristics of a structural epoxy. Composites: Part B 2016;88:55–63.10.1016/j.compositesb.2015.10.036
Search in Google Scholar Back to article
Silva P. (2017)Time-dependent behaviour and durability of RC slabs strengthened with NSM CFRP strips. Doctoral Thesis University of Minho, Portugal.
Search in Google Scholar Back to article
Stöcklin I. - Meier U. (2001)Strengthening of concrete structures with prestressed and gradually anchored CFRP strips. Presented at the 5th Int. conference on fibre-reinforced plastics for reinforced concrete structures (FRPRCS-5), Cambridge, UK, 16.-18. Juli 2001; Vol. 1, pp. 291-296.
Search in Google Scholar Back to article
Stöeklin I. - Meier U. (2003)Strengthening of concrete structures with prestressed and gradually anchored CFRP strips. Presented at the Sixth int. symposium on FRP reinforcement for concrete structures (FRPRCS-6), Singapore, July 8-10, 2003; Vol. 2, pp 1321-1330.10.1142/9789812704863_0127
Search in Google Scholar Back to article
Triantafillou T. C. - Deskovic N. – Deuring M. (1992)Strengthening of concrete structures with prestressed fiber reinforced plastic sheets. ACI Struct. J. 1992, 89 (3), 235-244.10.14359/2940
Search in Google Scholar Back to article

The Gradient Anchorage Method for Prestressed CFRP Strips: from the Development to the Strengthening of an 18 M Long Bridge Girder

Abstract

Paradigm

My account