Investigation of the Force Transfer Mechanisms for Open Hoop FRP Strips Bonded on R/C Beams with or without Anchoring Devices
- 1 Laboratory of Experimental Strength of Materials and Structures, Department of Civil Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece
- 2 Laboratory of Experimental Strength of Materials and Structures, Department of Civil Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece
Abstract
The present study investigates the force transfer mechanisms for open hoop fiber reinforced plastic (FRP) strips attached at reinforced concrete (R/C) beams with or without anchorage. These open hoop FRP strips are utilized in R/C beams that are in need of shear capacity upgrade. This type of retrofitting is necessary for R/C structures designed with less stringent seismic loading conditions than those currently required. For this purpose special unit beam concrete specimens were fabricated and were used to attach open hoop carbon (CFRP) or steel (SFRP) FRP strips with or without anchoring. A novel loading arrangement was utilized to apply the necessary forces to these unit beam specimens together with instrumentation capable of capturing the behaviour of these specimens up to failure. Studying in this way the transfer of forces from the open hoop FRP strips, it could be demonstrated that when this type of retrofitting was accompanied with a properly designed anchoring device, a significant increase in the bearing capacity of the tested specimens was observed. Moreover, the observed failure was that of the fracture of the FRP strips for all such specimens. The highest degree of FRP material exploitation was achieved in the specimen that utilizes a patented anchoring device together with two layers of SFRP strips. Debonding of the FRP strips or failure of the anchoring device results, as was to be expected, in relatively unsatisfactory FRP material exploitation.
- G. C. Manos, “Consequences on the Urban Environment in Greece Related to the Recent Intense Earthquake Ac tivity,” International Journal of Civil Engineering and Architecture, Vol. 5, No. 12, 2011, pp. 1065-1090.
- Eurocode-8, “Design of Structures for Earthquake Resistance, Part 2: Bridges,” European Committee for Standardization, 2004.
- Organization of Earthquake Planning and Protection of Greece (ΟΑSP), “Guidelines for Retrofitting in Reinforced Concrete Buildings,” Athens, 2011.
- G. C. Manos, K. Katakalos and V. Kourtides, “Construc tion Systeme for Strengthening an Existing Structure with Tension Sheets and a Respective Anchoring Device and Method Therefore,” Patent No: EP2336455-(A1), 2011.
- ACI 440.2R-08, “Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures,” American Concrete Institute, 2008.
- C. Bakis, et al., “Fiber-Reinforced Polymer Composites for Construction-State of the Art Review,” Journal of Composites of Construction, Vol. 6, No. 2, 2002, pp. 73-87.
- K. Katakalos, G. C. Manos and C. G. Papakonstantinou, “Comparison between Carbon and Steel Fiber Reinforced Polymers with or without Anchorage,” Proceedings of 6th International Conference on FRP Composites in Civil Engineering, Rome, 2012.
- K. Katakalos, “Strengthening of R/C Structures under High Cycle Fatigue Loadings,” LAP Lambert Academic Publishing GmbH & Co. KG, 2009.
- C. G. Papakonstantinou and K. Katakalos, “Flexural Be havior of Reinforced Concrete Beams Strengthened with a Hybrid Retrofit System,” Structural Engineering and Mechanics, Vol. 31, No. 5, 2009, pp. 225-252.
- K. Katakalos and C. Papakonstantinou, “Fatigue of Rein forced Concrete Beams Strengthened with Steel Rein forced Inorganic Polymers,” Journal of Composite for Construction, Vol. 13, No. 2, 2009, pp. 103-112. doi:10.1061/(ASCE)1090-0268(2009)13:2(103)
- G. C. Manos, K. Katakalos and C. Papakonstantinou, “Shear Behavior of Rectangular Beams Strengthened with Either Carbon or Steel Fiber Reinforced Polymers,” Ap plied Mechanics and Materials, Vol. 82, 2011, pp. 571-576. doi:10.4028/www.scientific.net/AMM.82.571
- G. C. Manos, K. Katakalos and V. Kourtides, “Study of the Anchorage of Carbon Fiber Plastics (CFRP) Utilized to Upgrade the Flexural Capacity of Vertical R/C Mem bers,” Proceedings of 14th WCEE, Beijing, 2008, pp. 1079-1095.