The application of a reinforced self-compacting concrete jacket for the structural rehabilitation of shear damaged reinforced concrete beams is experimentally investigated. Five beams were constructed and subjected to monotonic loading in order to exhibit shear failure. The damaged specimens were restored using relatively thin reinforced jackets and retested by the same four-point bending loading. The self-compacting concrete jacket applied, encasing the bottom width and both vertical sides of the initially tested beams (U-formed jacketing), has a small thickness (25？mm) and includes small ( 5) steel bars and U-formed stirrups. Test results and comparisons between the experimental behaviour of the beams indicated that the examined jacketing technique is a reliable rehabilitation method since the capacity of the retrofitted beams was fully restored or ameliorated with respect to the initial specimens. Discussion of the ability of the applied jacket to enhance the overall structural performance of the examined beams and, potentially, to alter their failure mode to a more ductile one is also included. Calculations of the flexural and shear strength of the tested beams and evaluation of the monolithic factors for the capacity at yield and at ultimate of the jacketed beams were also performed and are commented on. 1. Introduction One of the most commonly used rehabilitation techniques for poor detailed or damaged reinforced concrete (RC) members is the application of jackets around the structural elements. RC jacketing is a traditional and well-known upgrading technique that has proven to be the best option for engineers in earthquake-prone areas. It has long been recognized that RC jackets do provide increased strength, stiffness, and overall enhancement of the structural performance. For this reason, although common RC jacketing exhibits shortcomings, it is frequently used either prior to or after the damage of RC members, such as beams, columns, and joints [1–5]. The use of a shotcrete overlay on the surface of an existing RC member with an outer assembled reinforcement cage has also proved to be an efficient strengthening technique. Shotcrete jacketing can be used in lieu of conventional cast-in-place concrete jackets because of its potential to achieve good bond strength and low permeability. It is also known that the shotcrete process is more versatile than common concrete placement and can be applied in very difficult or complex sections where conventional concrete formwork would prove difficult, cost-prohibitive, or even impossible [2, 6]. Moreover,
References
[1]
G. E. Thermou, S. J. Pantazopoulou, and A. S. Elnashai, “Flexural behavior of brittle RC members rehabilitated with concrete jacketing,” Journal of Structural Engineering, vol. 133, no. 10, pp. 1373–1384, 2007.
[2]
S. N. Bousias, D. Biskinis, M. N. Fardis, and A. L. Spathis, “Strength, stiffness, and cyclic deformation capacity of concrete jacketed members,” ACI Structural Journal, vol. 104, no. 5, pp. 521–531, 2007.
[3]
F. Altun, “An experimental study of the jacketed reinforced-concrete beams under bending,” Construction and Building Materials, vol. 18, no. 8, pp. 611–618, 2004.
[4]
A. G. Tsonos, “Lateral load response of strengthened reinforced concrete beam-to-column joints,” ACI Structural Journal, vol. 96, no. 1, pp. 46–56, 1999.
[5]
K. G. Vandoros and S. E. Dritsos, “Concrete jacket construction detail effectiveness when strengthening RC columns,” Construction and Building Materials, vol. 22, no. 3, pp. 264–276, 2008.
[6]
A. D. G. Tsonos, “Performance enhancement of R/C building columns and beam-column joints through shotcrete jacketing,” Engineering Structures, vol. 32, no. 3, pp. 726–740, 2010.
[7]
G. E. Thermou, S. J. Pantazopoulou, and A. S. Elnashai, “Global interventions for seismic upgrading of substandard RC buildings,” Journal of Structural Engineering, vol. 138, no. 3, pp. 387–401, 2012.
[8]
T. Georgopoulos and S. E. Dritsos, “A steel jacketing technique for strengthening RC columns,” in Proceedings of the 10th European Conference on Earthquake Engineering, pp. 2275–2280, Vienna, Austria, 1994.
[9]
C. E. Chalioris, “Torsional strengthening of rectangular and flanged beams using carbon fibre-reinforced-polymers—experimental study,” Construction and Building Materials, vol. 22, no. 1, pp. 21–29, 2008.
[10]
C. G. Karayannis and G. M. Sirkelis, “Strengthening and rehabilitation of RC beam-column joints using carbon-FRP jacketing and epoxy resin injection,” Earthquake Engineering and Structural Dynamics, vol. 37, no. 5, pp. 769–790, 2008.
[11]
T. C. Triantafillou and C. G. Papanicolaou, “Shear strengthening of reinforced concrete members with textile reinforced mortar (TRM) jackets,” Materials and Structures, vol. 39, no. 285, pp. 93–103, 2006.
[12]
D. A. Bournas and T. C. Triantafillou, “Flexural strengthening of reinforced concrete columns with near-surface-mounted FRP or stainless steel,” ACI Structural Journal, vol. 106, no. 4, pp. 495–505, 2009.
[13]
C. G. Karayannis, C. E. Chalioris, and G. M. Sirkelis, “Local retrofit of exterior RC beam-column joints using thin RC jackets—an experimental study,” Earthquake Engineering and Structural Dynamics, vol. 37, no. 5, pp. 727–746, 2008.
[14]
K. H. Khayat, “Workability, testing, and performance of self-consolidating concrete,” ACI Materials Journal, vol. 96, no. 3, pp. 346–353, 1999.
[15]
A. S. Georgiadis, K. K. Sideris, and N. S. Anagnostopoulos, “Properties of scc produced with limestone filler or viscosity modifying admixture,” Journal of Materials in Civil Engineering, vol. 22, no. 4, pp. 352–360, 2010.
[16]
T. Albanesi, D. Lavorato, C. Nuti, and S. Santini, “Experimental tests on repaired and retrofitted bridge piers,” in Proceedings of the International FIB Symposium, pp. 673–678, Amsterdam, The Netherlands, 2008.
[17]
C. G. Fakitsas, P. E. A. Papakonstantinou, P. D. Kiousis, and A. Savva, “Effects of recycled concrete aggregates on the compressive and shear strength of high-strength self-consolidating concrete,” Journal of Materials in Civil Engineering, vol. 24, no. 4, pp. 356–361, 2012.
[18]
K. M. Heiza, N. N. Meleka, and N. Y. Elwkad, “Behavior and analysis of self-consolidated reinforced concrete deep beams strengthened in shear,” Journal of ISRN Civil Engineering, vol. 2012, Article ID 202171, 14 pages, 2012.
[19]
K. K. Sideris, A. S. Georgiadis, N. S. Anagnostopoulos, and P. Manita, “Low strength self compacting concrete for building application,” in Proceedings of the International FIB Symposium, pp. 1057–1059, Amsterdam, The Netherlands, 2008.
[20]
C. G. Karayannis, C. E. Chalioris, and K. K. Sideris, “Effectiveness of RC beam-column connection repair using epoxy resin injections,” Journal of Earthquake Engineering, vol. 2, no. 2, pp. 217–240, 1998.
[21]
C. E. Chalioris, C. N. Pourzitidis, C. P. Papadopoulos, and D. Fotis, “Flexural rehabilitation of RC beams using self-compacting concrete jacketing,” Proceedings of the 2nd International Conference on Civil Engineering and Building Materials, Hong Kong, 2012, Paper ID 257.
[22]
F. J. Vecchio and M. P. Collins, “The modified compression field theory for reinforced concrete elements subjected to shear,” Journal of the American Concrete Institute, vol. 83, no. 2, pp. 219–231, 1986.
[23]
E. Bentz and M. P. Collins, Response-2000 Reinforced Concrete Sectional Analysis Using the Modified Compression Field Theory, Version 1. 0. 5, Software Package, University of Toronto, 2000.
[24]
P. D. Zararis, “Shear compression failure in reinforced concrete deep beams,” Journal of Structural Engineering, vol. 129, no. 4, pp. 544–553, 2003.
[25]
P. D. Zararis and G. C. Papadakis, “Diagonal shear failure and size effect in RC beams without web reinforcement,” Journal of Structural Engineering, vol. 127, no. 7, pp. 733–742, 2001.
[26]
P. D. Zararis, “Shear strength and minimum shear reinforcement of reinforced concrete slender beams,” ACI Structural Journal, vol. 100, no. 2, pp. 203–214, 2003.
