Local Impact Damage Response of CFRP Strengthened Concrete Slabs

The effectiveness of carbon fiber reinforced polymer (CFRP) strengthening is well established for seismic retrofitting and structurally deficient RC members, however their response to impact loads is not well known. This paper attempts to investigate the local damage behavior of CFRP strengthened RC slabs against projectile impact. In the present study, CFRP strengthened RC slabs were tested under the impact of 40 mm diameter projectile with hemispherical nose and the response was compared with the control. The test specimens were 600 mm square, 90 mm thick RC slabs reinforced with 8 mm diameter steel rebars. The velocity of steel projectiles was varied within sub-ordinance range and the projectile was made to strike normal to the slab using a gas gun. The slabs were also tested under quasi-static load for establishing their punching resistance against the same projectiles. The test results illustrate that CFRP strengthening is effective in reducing the local damage from front and rear faces of RC slabs. Moreover, the strengthening increases the ballistic limit velocity by 18% and the energy absorption in quasi-static punching by 65.5%. The CFRP strengthening is also effective in reducing the flying of concrete fragments from the rear face.