Punching Strengthening of Concrete Slab-column Connections Using Near Surface Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) Bars

Main Article Content

Ahmed H. Abdel-Kareem

Abstract

This paper investigates experimentally the effect of near surface mounted (NSM) carbon fiber reinforcement polymer (CFRP) bars as externally strengthening on the punching shear behavior of interior slab-column connections. Many researchers used NSM as a novel strengthening technique in various structural elements. However, the strengthening of slab-column connections using NSN is relatively new. Seven Reinforced concrete (RC) square slabs with a concentric column were tested over simply supported four sides. One control specimen was tested without strengthening, four specimens were strengthened using NSM-CFRP bar installed in pre-cut groove surrounded the column at the tension side of the slab, and two specimens were strengthened using externally bonded (EB) CFRP strips which have the same tensile force of the CFRP bars. The arrangement and the location of the strengthened materials were also test variables. The test results showed that using NSM strengthening technique significantly increased the punching shear capacity and ultimate stiffness compared to using EB strengthening technique. Where the increasing in the punching capacity and ultimate stiffness were 18% and 13-18%, respectively. Moreover, the NSM-CFRP bars greatly reduced the cracks in the punching shear zone around the columns. The measured ultimate punching shear capacity for the tested specimens showed very reasonable agreement with the calculated punching loads based on an analytical model for slab-column connections strengthened using FRP that account for its arrangement and location.  

Keywords:
Slab-column, punching shear, strengthening, near surface mounted, CFRP, external bonded.

Article Details

How to Cite
H. Abdel-Kareem, A. (2020). Punching Strengthening of Concrete Slab-column Connections Using Near Surface Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) Bars. Journal of Engineering Research and Reports, 9(2), 1-14. https://doi.org/10.9734/jerr/2019/v9i217013
Section
Original Research Article

References

Malalanayake MLVP, Gamage JCPH, Silva MAL. Experimental investigation on enhancing punching shear capacity of flat slabs using CFRP. 8th International Conference on Structural Engineering and Construction Management (ICSECM2017), Kandy, Sri Lanka; 2017.

Abdullah A, Bailey CG, Wu ZJ. Tests investigating the punching shear of a column slab connection strengthened with non-prestressed or prestressed FRP plates. Constr Build Mater. 2013;48:1134–44.

Silva MAL, Gamage JCPH, Fawzia S. Performance of slab-column connections of flat slabs strengthened with carbon fiber reinforced polymers. Case Studies in Constr Mater. 2019;11.

Dissanayaka RHM, Silva MAL, Magallagoda LPG, Gamage JCPH. Physical behavior of CFRP retrofitted reinforced concrete slab-column connec-tions. 9th International Conference on Sustainable Built Environment (ICSBE2018), Kandy, Sri Lanka; 2018.

Esfahani MR, Kianoush MR, Moradi AR. Punching shear strength of interior slab–column connections strengthened with carbon fiber reinforced polymer sheets. Eng Struct. 2009;31(7):1535–1542.

Soudki K, El-Sayed A, Vanzwol T. Strengthening of concrete slab-column connections using CFRP strips. J King Saud Univ Eng Sci. 2012;24(1):25–33.

Askar H. Repair of R/C flat plates failing in punching by vertical studs. Alexand Eng J. 2015;54(3):541–50.

Meisami HM, Davood M, Hikaru N. Punching shear strengthening of two-way flat slabs with CFRP grids. J Compos Constr. ASCE. 2014;18.

Inácio M, Ramos A, Faria D. Strengthening of flat slabs with transverse reinforcement by introduction of steel bolts using different anchorage approaches. Eng Struct. 2012; 44:63–77.

Ruiz M, Muttoni A, Kunz J. Strengthening of flat slabs against punching shear using post-installed shear reinforcement. ACI Struct J. 2011;434–42.

Hikmatullah A, Ted D, Diana P. Strengthening of slab-column connection against punching shear failure with CFRP laminates. Compos Struct. 2019; 208.

Sharaky IA, Torre L, Sallam HE. Experimental and analytical investigation into the flexural performance of RC beams with partially and fully bonded NSM FRP bars/strips. Compos Struct. 2015;122:113–126.

Sharaky IA, Torres L, Comas J, Barris C. Flexural response of reinforced concrete (RC) beams strengthened with near surface mounted (NSM) fibre reinforced polymer (FRP) bars. Compos Struct. 2014; 109:8–22.

Almusallam TH, Elsanadedy HM, Al-Salloum YA, Alsayed SH. Experimental and numerical investigation for the flexural strengthening of RC beams using near-surface mounted steel or GFRP bars. Constr Build Mater. 2013;40:45–161.

Kotynia R. Bond between FRP and concrete in reinforced concrete beams strengthened with near surface mounted and externally bonded reinforcement. Constr Build Mater. 2012;32:41–54.

Sun ZY, Wu G, Wu ZS, Luo YB. Flexural strengthening of concrete beams with near-surface mounted steel-fiber-reinforced polymer composite bars. J Reinf Plast Compos. 2011;1529–37.

Abdel-kareem AH, Debaiky AS, Makhlouf MH, Abdel-baset M. Shear Strengthening of RC Beams with FRP using (NSM) Technique. Advances in Research, SCIENCEDOMAIN international. 2019; 19(4):1-20.

Rizzo A, De Lorenzis L. Behavior and capacity of RC beams strengthened in shear with NSM FRP reinforcement. Constr Build Mater. 2009;23(4):1555–67.

Rahal KN, Rumaih HA. Tests on reinforced concrete beams strengthened in shear using near surface mounted CFRP and steel bars. Eng Struct. 2011;33(1):53–62.

Meysam J, Sharbatdar MK, Jian-Fei C, Farshid JA. Shear strengthening of RC beams using innovative manually made NSM FRP bars. Constr Build Mater. 2012; 36:990–1000.

Harajli MH, Soudki KA. Shear streng-thening of interior slab-column connections using fiber reinforced polymer sheets. J Compos Constr ASCE. 2003; 7(2):145–53.

CSA Committee A23.3. Design of concrete structure. Canadian Standards Association. Mississauga. Ontario, Canada; 2004.

Sharaf MH, Soudki KA, Van Dusen M. CFRP strengthening for punching shear of interior slab-column connections. J Compo Constr ASCE. 2006;10(5);410–18.

Elstner RC, Hognestad E. Shearing strength of reinforced concrete slabs. ACI Journal Proceedings. 1956;53(2):29–58.

Mowrer RD, Vanderbilt MD. Shear strength of light-weight aggregate reinforced concrete flat plates. ACI Journal Proceedings. 1967;64(11):722–29.