How to Cite
Abstract
The research program included 8 RC beams with the cross-section of 150300mm and span of 3000mm. The beams were differed in steel reinforcement ratio, length, location and type of the CFRP strip. The strips of type S and M with the modulus of elasticity 170GPa and 210 GPa were used in the research. In order to improve anchorage conditions of the main strip additional strips were bonded to the both sides of two beams at the support region. The beams were loaded with two forces (series I – 6 elements) or one force located in the middle of the beam span (series II – 2 elements). The strip debonding caused failure of all beams.
Two modes of failure differing in position and image of de-bonded strip appeared in tests. The first one (“P”) was appeared in the support region close to the end of the strip. The strip de-bonded together with concrete cover on short distance included only support region and did not reach the load point. The second mode of failure (“Z”) was distinguished longer debonding distance of the strip included both support and pure bending region. In this case de-bonding of the strip occurred by delamination in the adhesive layer and only locally in the concrete cover.
The result of the research indicated that tension strength of the strip couldn’t be reached because of its earlier de-bonding from the beam surface. Strengthening ratio of the beam can be sufficient especially for elements with low steel reinforcement ratio. Strengthening effect can be increased by application of the strip with high elasticity modulus or strip prestressing before bonding to the element. Nonlinear-elastic-plastic model of concrete with tension stiffening principle was assumed in computational analysis.
References
Brandt A. M., “O zastosowaniu uzbrojenia i sprężania konstrukcji prętami, cięgnami taśmami z materiałów kompozytowych”. XLII Konferencja naukowa Komitetu Inżynierii Lądowej i Komitetu Nauki PZiTB, Kraków - Krynica 1996, s. 169-174.
Karta Techniczna nr 01; System Sika®CarboDur, Dokument nr: DZT/0004/15.01.1998.
Kamińska M. E., Kotynia R., Kozicki J., “O wpływie skracania zbrojenia podłużnego na nośność belek żelbetowych”, Proc. XLV Konferencji Naukowej KIL i W PAN i KN PZITB, Krynica’96, t. 4, s. 45-52.
Czkwianianc A., Kamińska M. E., “Metoda nieliniowej analizy żelbetowych elementów prętowych”, Proc. KILiW PAN IPPT, Studia z Zakresu Inżynierii nr 36, Warszawa 1993, s. 130.
Nanni A., DiTomasso A., Arduini M.: Behavior of RC Beams Strengthened with Carbon FRP Sheets, Research Report Part II. Continuous Beams, University of Bologna, pp. 1-16, Italy 1997.
Kotynia R., “Niektóre aspekty wzmacniania belek na zginanie taśmami CFRP”, Proc. XLIII Konferencji Naukowej KIL i W PAN i KN PZITB, Krynica’97, t. 4, s. 117-124.
M’Bazaa I., Misshoun, M., Labossiére P., „Strengthening of reinforced concrete beams with CFRP Sheets”, Fiber Composites in Infrastructure, ICCI’96 January, 1996, pp. 746 - 759.
Malek A. M, Saadatmanesh H., Design Equations and Guidelines for Reinforced Concrete Beams Strengthened with FRP Plates,” Proceedings of the Second International Conference on Composite in Infrastructure ICCI’98, Fiber Composite in Infrastructure, pp.603-616.
Malek A. M., Saadatmanesh H., Ehsani M. R., „Prediction of Failure Load of R/S Beams Strengthened with FRP Plate Due to Stress Concentration at the Plate End”, ACI Structural Journal Vol 95 (1), March - April 1998, pp. 142- 152.
Meier U., “Composites for Structural Repair and Retrofitting”, Proceedings of the First International Conference on Fiber Composites in Infrastructure, ICCI 1996, pp.1202-1216.
Norris T., Saadatmanesh H., Ehsani M. R., „Shear and Flexural Strengthening of R/C Beams with Carbon Fiber Sheets”, Journal of Structural Engineering, July 1997, pp. 903 - 911.
Ross A., Jermore D.M., Tedesco J.W., Hughes M. L., “Strengthening of Reiforced Concrete Beams with Externally Bonded Composite Laminates”, ACI Structural Journal March-April 1999, Vol. 96, No.2, pp. 212-220.
Radomski W., „Nowe materiały w mostownictwie”, XLV Konferencja Naukowa Komitetu Inżynierii Lądowej i Wodnej PAN i Komitetu Nauki PZITB, Wrocław-Krynica 1999, Tom 6, s. 281-302.
Brosens K., Van Gemert D., „Anchorage Design for Externally Bonded Carbon Fiber Reinforced Polymer Laminates”, Fourth International Symposium Fiber Reinforced Polymer Reinforcement for Reiforced Concrete Structures, ACI 1999, p.p.635 - 645.
Cichocki M., „Odkształcalność i nośność zarysowanych belek żelbetowych wzmocnionych taśmami kompozytowymi CFRP”, Inż. i Bud. nr 12/99 s. 698 – 703.
Kamińska M.E., Kotynia R., „ Tests of RC beams strengthened with CFRP Plates”, IABSE - Colloquium, Saving Buildings in Central and Eastern Europe, Berlin 1998 r.
Kamińska M. E., Kotynia R., „Stan graniczny nośności przy zginaniu żelbetowych belek wzmocnionych taśmami CFRP”, XLIV Konferencja Naukowa KILiW PAN,, t. 4, s. 95-102, Krynica 1998 r.
Kamińska M. E., Kotynia R., Discussion (96-S23/From the March-April 1999, ACI Structural Journal, 212-220) for paper by C. Allen Ross, David M. Jerome, Joseph W. Tedesco, and Mary L. Hughes , „Strengthening of Reinforced Concrete Beams with Externally Bonded Composite Laminates”, ACI Structural Journal, pp. 204-205, January - February 2000.
Kotynia R., „Load bearing capacity and strains of reinforced concrete beams strengthened with carbon composite plates”, 3rd International PhD Symposium in Civil Engineering, v. II, pp. 193- 202 ,Vienna 2000.