Strengthening of slab-column connection against punching shear failure with CFRP laminates

Akhundzada, Hikmatullah; Donchev, Ted; Petkova, Diana

doi:10.1016/j.compstruct.2018.09.076

Cited by 28 publications

(15 citation statements)

References 9 publications

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“…Brittle in behavior, it exhibits a unique tensile strength higher than steel with their weight equal to one-quarter of steel [13]. Field applications have shown excellent performance and durability of FRP retrofitted structures [14][15][16][17][18][19][20][21][22][23][24][25]. FRP strips were bonded "On Grooves" (EBROG) and "In Grooves" (EBRIG).…”

Section: Introductionmentioning

confidence: 99%

Remediation of Punching Shear Failure Using Glass Fiber Reinforced Polymer (GFRP) Rods

et al. 2021

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The results of an experimental program on shear-strengthening of flat slabs using Glass Fiber Reinforced Polymer (GFRP) rods are presented. A total of seven specimens were tested under an upward concentric monotonic loading until failure. One specimen served as a control and was tested without any modification. The remaining six specimens were strengthened with post-installed GFRP rods in single (SG), double (DB), and radial (RD) patterns within shear critical parameters around the centric column. The results of this experimental study suggest that GFRP rods are capable of enhancing both the peak load and deformation capacity. Furthermore, brittle failure associated with punching shear failure was successfully avoided by all strengthening patterns. Of all of the patterns, the RD pattern resulted in maximum peak load increase and corresponding deformation capacity while the lowest bound was created by the SG pattern. The results suggested that SG, DB and RD patterns enhanced ultimate loads up to 9.1, 11.3 and 15.7% while corresponding deflections increased up to 109, 136 and 154%. Strain measurement on flexural reinforcement suggested that all strengthened specimens were able to withstand higher longitudinal strains than yield. It was further shown that reducing the spacing between the GFRP rods efficiently enhanced peak loads, nevertheless, neither this change was proportional, nor did it result in an enhanced energy dissipation capacity. In the end, recommendations of American Concrete Institute (ACI) for the shear strength of two-way systems were modified to incorporate the contributions from GFRP rods. The results indicate that the proposed analytical approach provides an excellent match with the experimental results.

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Section: Introductionmentioning

confidence: 99%

Remediation of Punching Shear Failure Using Glass Fiber Reinforced Polymer (GFRP) Rods

et al. 2021

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“…The ordinary failure for applying the external strengthening technique was the hasty decrypting of CFRP. Decrypting could be delayed developing the structural attitude of strengthened connection via supplying a final berth to the external connected FRP [11]. Post-installation of CFRP shear bolts, as shear strengthening, in penetrated holes were stuffed with suitable epoxy cement.…”

Section: Strengthening Of Flat Slabs Connection With Edge Columns Against Punching Shear Using Near Surface Mounted (Nsm) Carbon Fiber Rementioning

confidence: 99%

Strengthening of Flat Slabs Connection With Edge Columns Against Punching Shear Using Near Surface Mounted (Nsm) Carbon Fiber Reinforced Polymer (Cfrp) Bars

Ibrahim

Hamdy

Hasan

2021

Journal of Al-Azhar University Engineering Sector

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This paper discuses analytically and by experimentation the influence of near surface mounted (NSM) carbon fiber reinforcement polymer (CFRP) bars, which acted as an external strength, on the punching shear attitude of edge slab-column bonds. It was stated that many researchers used NSM as a new strengthening technique in different constructional elements. Nevertheless, the strengthening of edge slab-column connections that used NSM was the same and was also used for cardinal slab column connection by first author. Seven Reinforced concrete (RC) square slabs with a bordered column were tested. The specimens were buttressed at the column -as an axis point -and at supportive line on the opposite side of the column. One control specimen was tested without strengthening, four specimens were strengthened using NSM-CFRP bar fitted into pre-dug pothole positioned around the column at the tension side of the slab, and two specimens were strengthened using external Bonded (EB) CFRP strips. The (EB) CFRP strips have the same tensile force of the CFRP bars. The place and area of strength to the strengthened materials were also tested differently. The results of the investigation demonstrated that the use of NSM strengthening technique increased the punching shear capacity and ultimate stiffness appreciably compared to that of applying EB strengthening technique. There were ascending outcomes in the punching shear capacity and ultimate stiffness as 9%-15% and 4%-11% respectively. Furthermore, the cracks in the punching shear zone around the columns were remarkably lowered by the NSM-CFRP bars. The measured ultimate punching shear capacity for the tested specimens proved very rational accordance with the calculated punching loads. This capacity based mainly on a diagnostic specimen for edge slab-column connections strengthened by using FRP concerning its area of bars and place from face of column.

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“…This strengthening method increases the flexural reinforcement and therefore increases the punching shear strength by delaying the shear cracks formation. The common failure for external strengthening technique is the premature debonding of FRP, which could be delayed and improve the structural behavior of strengthened connection by providing end anchorage to the externally bonded FRP [5].Post-installation of FRP studs or FRP shear dowels, as shear reinforcement, in drilled holes filled with suitable epoxy grout falls into internal strengthened method for slab-columns connections. The drilled holes, to insert shear reinforcement, in the critical punching shear area of the slab near the column could further damage the degenerated slab.…”

Section: Introductionmentioning

confidence: 99%

Punching strengthening of reinforced concrete slab-Column connection using different techniques

Khaleel¹,

Kareem²,

Debaiky³

et al. 2022

IJAEMS

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This paper presents experimental data and results on the effect of externally bonded fiberreinforced polymer (FRP) with studs from FRB on the punching shear behavior of interior slab-column connections. A total of sixteen square slabs with a concentric column were constructed and tested. One specimen act as a control, and the others specimens strengthened with three different strengthening techniques. The first technique consists of 6 slabs strengthened with external FRB strips with different configuration (skewed or orthogonal) and different location from column face (offset or adjacent) and the second technique consist of 4 slab strengthened with external FRB strips with studs from FRP located on both side of the strips with spacing 100 mm and cross at intersection of strips which act as shear reinforcement and wrapping FRP strips to delayed debonding of FRP and improve the structure behavior of strengthened connection. The third technique consists of 5 slabs strengthened with external FRB and steel plates with different size 350 x 350 mm and 450 x 450 mm at the center of the slab. The test variables were the location of FRP strips (adjacent or offset column face), the number of strips layer and the orientation angle of the strips (Orthogonal and Skewed), and the type of materials (GFRP, CFRP, Steel). Size of plate 350 x 350 mm or 450 x 450 mm and method of strengthening. The test results clearly showed that FRP with studs strengthening leads to significant improvements in the structural behavior of slabcolumn connections. The increase in punching capacity of strengthened slabs was up to 48%, while the increase in stiffness was up to 92% compared to the control slab.

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Strengthening of slab-column connection against punching shear failure with CFRP laminates

Cited by 28 publications

References 9 publications

Remediation of Punching Shear Failure Using Glass Fiber Reinforced Polymer (GFRP) Rods

Remediation of Punching Shear Failure Using Glass Fiber Reinforced Polymer (GFRP) Rods

Strengthening of Flat Slabs Connection With Edge Columns Against Punching Shear Using Near Surface Mounted (Nsm) Carbon Fiber Reinforced Polymer (Cfrp) Bars

Punching strengthening of reinforced concrete slab-Column connection using different techniques

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