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 NSMCFRP
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. |
