عنوان مقاله [English]
Extending service life and preventing demolition of existing structures are the primary goals of structural strengthening and rehabilitation. Fiber-reinforced polymer (FRP) composites have been the most common type of composite in the realm of structural strengthening applications. In recent years, as a new type of composite, epoxy is replaced by an inorganic matrix, named fiber reinforced cementitious mortar (FRCM), and have attracted a great deal of interest among researchers. Focusing of these kind of novel composites, this paper tries to find a connection between FRCM composites behaviour, as their maximum fiber strain, in flexural and direct shear tests. To achieve this goal, a cross section analysis of previous research works on strengthened RC beams with one layer of composites was conducted and the maximum strain of the fibers was obtained. Calculated fiber strains in flexural strengthening specimens compared with corresponding measured maximum fiber strains in direct shear test specimens. Comparison of results show that the average of maximum fiber strain obtained from flexural specimens is in good agreement with corresponding one measured in direct shear test specimens. Consequently, maximum fiber strains could be designated as the lost link between flexural and direct shear tests as two separated part of a chain.
 O. Buyukozturk and B. Hearing, “Failure behavior of precracked concrete beams retrofitted with FRP,” J. Compos. Constr., vol. 2, no. 3, pp. 138–144, 1998.
 A. D’Ambrisi and F. Focacci, “Flexural Strengthening of RC Beams with Cement-Based Composites,” J. Compos. Constr., vol. 15, no. 5, pp. 707–720, 2011.
 A. Foden, P. Balaguru, R. Lyon, and J. Davidovits, “High temperature inorganic resin for use in fiber reinforced composites,” in First International Conference on Composites in Infrastructure, 1996.
 L. A. Bisby, E. C. Roy, M. Ward, and T. J. Stratford, “Fibre reinforced cementitious matrix systems for fire-safe flexural strengthening of concrete: pilot testing at ambient temperature,” Proc. Adv. Compos. Constr. Edinburgh, UK, 2009.
 F. J. y Basalo, A. Nanni, and J. P. James, “Qualitative and quantitative environmental impact analysis of BFRC vs GFRP: green building construction rehabilitation systems,” in Engineering sustainability conference. Pittsburgh (PA), 2009.
 A. Wiberg, “Strengthening of concrete beams using cementitious carbon fibre composites,” Byggvetenskap, 2003.
 S. Pareek, Y. Suzuki, and A. Kobayashi, “Flexural and shear strengthening of RC beams using newly developed CFRP and polymer-cement pastes as bonding agents,” Proc. Fiber-Reinforced Polym. Reinf. Concr. Struct. FRPRCS-8, Patras, Greece, 2007.
 B. Täljsten and T. Blanksvärd, “Mineral-based bonding of carbon FRP to strengthen concrete structures,” J. Compos. Constr., vol. 11, no. 2, pp. 120–128, 2007.
 T. Triantafillou, “Innovative textile-based composites for strengthening and seismic retrofitting of concrete and masonry structures,” in Advances in FRP Composites in Civil Engineering, Springer, 2011, pp. 3–12.
 S. Hashemi and R. Al-Mahaidi, “Experimental and finite element analysis of flexural behavior of FRP-strengthened RC beams using cement-based adhesives,” Constr. Build. Mater., vol. 26, no. 1, pp. 268–273, 2012.
 A. D’Ambrisi, F. Focacci, R. Luciano, V. Alecci, and M. De Stefano, “Carbon-FRCM materials for structural upgrade of masonry arch road bridges,” Compos. Part B Eng., vol. 75, pp. 355–366, 2015.
 A. Napoli and R. Realfonzo, “Reinforced concrete beams strengthened with SRP/SRG systems: experimental investigation,” Constr. Build. Mater., vol. 93, pp. 654–677, 2015.
 Z. C. Tetta, L. N. Koutas, and D. A. Bournas, “Shear strengthening of full-scale RC T-beams using textile-reinforced mortar and textile-based anchors,” Compos. Part B Eng., vol. 95, pp. 225–239, 2016.
 T. D’Antino and C. Papanicolaou, “Mechanical characterization of textile reinforced inorganic-matrix composites,” Compos. Part B Eng., 2017.
 L. Ombres, “Failure modes in reinforced concrete beams strengthened with PBO fiber reinforced mortars,” Proc. Fiber-Reinforced Polym. Reinf. Concr. Struct. FRPRCS-9, Sydney, Aust., 2009.
 L. Ombres, “Flexural analysis of reinforced concrete beams strengthened with a cement based high strength composite material,” Compos. Struct., vol. 94, no. 1, pp. 143–155, 2011.
 G. Loreto, L. Leardini, D. Arboleda, and A. Nanni, “Performance of RC Slab-Type Elements Strengthened with Fabric-Reinforced Cementitious-Matrix Composites,” Am. Soc. Civ. Eng., pp. 1–9, 2013.
 S. Babaeidarabad, G. Loreto, and A. Nanni, “Flexural Strengthening of RC Beams with an Externally Bonded Fabric-Reinforced Cementitious Matrix,” J. Compos. Constr., pp. 1–12, 2014.
 E. Tzoura and T. C. Triantafillou, “Shear strengthening of reinforced concrete T-beams under cyclic loading with TRM or FRP jackets,” Mater. Struct., vol. 49, no. 1–2, pp. 17–28, 2016.
 H. M. Elsanadedy, T. H. Almusallam, S. H. Alsayed, and Y. A. Al-Salloum, “Flexural strengthening of RC beams using textile reinforced mortar--Experimental and numerical study,” Compos. Struct., vol. 97, pp. 40–55, 2013.
 M. Santandrea, G. Quartarone, C. Carloni, and X. L. Gu, “Confinement of Masonry Columns with Steel and Basalt FRCM Composites,” in Key Engineering Materials, 2017, vol. 747, pp. 342–349.
 A. Brückner, R. Ortlepp, and M. Curbach, “Textile reinforced concrete for strengthening in bending and shear,” Mater. Struct. Constr., vol. 39, no. 292, pp. 741–748, 2006.
 L. N. Koutas and D. A. Bournas, “Flexural strengthening of two-way RC slabs with textile-reinforced mortar: experimental investigation and design equations,” J. Compos. Constr., p. 4016065, 2016.
 S. Weiland, R. Ortlepp, and M. Curbach, “Strengthening of predeformed slabs with textile reinforced concrete,” in Proceedings of the second International fib-Congress CEB-FIP, 2006.
 J. H. Gonzalez-Libreros, C. Sabau, L. H. Sneed, C. Pellegrino, and G. Sas, “State of research on shear strengthening of RC beams with FRCM composites,” Constr. Build. Mater., vol. 149, pp. 444–458, 2017.
 W. M. Sebastian, “Significance of midspan debonding failure in FRP-plated concrete beams,” J. Struct. Eng., vol. 127, no. 7, pp. 792–798, 2001.
 L. H. Sneed, S. Verre, C. Carloni, and L. Ombres, “Flexural behavior of RC beams strengthened with steel-FRCM composite,” Eng. Struct., vol. 127, pp. 686–699, 2016.
 P. A. Ritchie, D. A. Thomas, L.-W. Lu, and G. M. Connelly, “External reinforcement of concrete beams using fiber-reinforced plastics,” 1990.
 A. Sharif, G. J. Al-Sulaimani, I. A. Basunbul, M. H. Baluch, and B. N. Ghaleb, “Strengthening of initially loaded reinforced concrete beams using FRP plates,” Struct. J., vol. 91, no. 2, pp. 160–168, 1994.
 M. Arduini, A. Di Tommaso, and A. Nanni, “Brittle failure in FRP plate and sheet bonded beams,” ACI Struct. J., vol. 94, no. 4, pp. 363–370, 1997.
 M. J. Chajes, W. W. Finch, T. F. Januszka, and T. A. Thomson, “Bond and force transfer of composite material plates bonded to concrete,” ACI Struct. J., vol. 93, no. 2, pp. 208–217, 1996.
 B. Täljsten, “Defining anchor lengths of steel and CFRP plates bonded to concrete,” Int. J. Adhes. Adhes., vol. 17, no. 4, pp. 319–327, 1997.
 L. Bizindavyi and K. W. Neale, “Transfer lengths and bond strengths for composites bonded to concrete,” J. Compos. Constr., vol. 3, no. 4, pp. 153–160, 1999.
 J. F. Chen and J. G. Teng, “Anchorage strength models for FRP and steel plates bonded to concrete,” J. Struct. Eng., vol. 127, no. 7, pp. 784–791, 2001.
 L. H. Sneed, T. D’Antino, C. Carloni, and C. Pellegrino, “A comparison of the bond behavior of PBO-FRCM composites determined by double-lap and single-lap shear tests,” Cem. Concr. Compos., vol. 64, no. November, pp. 37–48, 2015.
 F. G. Carozzi and C. Poggi, “Mechanical properties and debonding strength of Fabric Reinforced Cementitious Matrix (FRCM) systems for masonry strengthening,” Compos. Part B Eng., vol. 70, 2015.
 J. Donnini, V. Corinaldesi, and A. Nanni, “Mechanical properties of FRCM using carbon fabrics with different coating treatments,” Compos. Part B Eng., vol. 88, 2016.
 T. D’Antino, L. H. Sneed, C. Carloni, and C. Pellegrino, “Effect of the inherent eccentricity in single-lap direct-shear tests of PBO FRCM-concrete joints,” Compos. Struct., vol. 142, 2016.
 E. Nigro, G. Cefarelli, A. Bilotta, G. Manfredi, and E. Cosenza, “Guidelines for flexural resistance of FRP reinforced concrete slabs and beams in fire,” Compos. Part B Eng., vol. 58, pp. 103–112, 2014.
 M. Curbach, R. Ortlepp, and T. C. Triantafillou, “TRC for rehabilitation,” Text. Reinf. Concr., pp. 221–236, 2006.
 L. Ombres, A. Trimboli, G. Mantegazza, and A. Gatti, “Strengthening of old reinforced concrete structures using fiber reinforced cementitious mortars (FRCM): A case study,” Proceeding, fiber-reinforced Polym. Reinf. Concr. Struct. FRPRCS-9, Sydney, Aust., 2009.
 L. Ombres, “Analysis of the bond between Fabric Reinforced Cementitious Mortar (FRCM) strengthening systems and concrete,” Compos. Part B Eng., vol. 69, pp. 418–426, 2015.
 T. D’Antino, C. Carloni, L. H. Sneed, and C. Pellegrino, “Matrix-fiber bond behavior in PBO FRCM composites: A fracture mechanics approach,” Eng. Fract. Mech., vol. 117, 2014.
 A. D’Ambrisi, L. Feo, and F. Focacci, “Experimental analysis on bond between PBO-FRCM strengthening materials and concrete,” Compos. Part B Eng., vol. 44, no. 1, pp. 524–532, Jan. 2013.
 N. G. Bunni, B. D. SCOTT, R. PARK, and M. J. N. PRIESTLEY, “STRESS-STRAIN BEHAVIOR OF CONCRETE CONFINED BY OVERLAPPING HOOPS AT LOW AND HIGH-STRAIN RATES-DISCUSSION,” J. Am. Concr. Inst., vol. 79, no. 6, pp. 496–498, 1982.
 ACI 440.2R, Guide for the Design and Construction of Externally Bonded FRP Systems. 2008.