Strengthening of flat slabs connection with edge columns against punching shear using near surface mounted (NSM)‎ carbon fiber reinforced polymer (CFRP)‎ bars

Abstract EN

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 slwith abordered column were tested.

The specimens were buttressed at the column -as anaxis 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.