Bond-slip effect in flexural behavior of GFRP RC slabs

The use of glass fiber reinforced polymer (GFRP) composite bars as internal reinforcement for concrete is rapidly increasing especially in structures exposed to aggressive environments. A proper bond mechanism between GFRP bar and concrete is essential to ensure proper functioning of such structures. The slippage between the concrete and reinforcement has usually been ignored in numerical modeling of reinforced concrete (RC) structures. In this study, the effect of the bond action in flexural behavior of GFRP RC slabs was investigated. The analysis was first performed by considering a perfect bond between the concrete and reinforcement and ignoring any slippage. Next, an experimentally obtained bond-slip relation was used to replace the unrealistic perfect bond assumption. The predicted flexural load-deflection response of the slab was compared to the experimental data. The result obtained by incorporating the bond-slip model showed a better agreement with the experimental data. Hence, considering the slippage between the GFRP and concrete may be necessary when accurate deflection estimate is required under the service condition. Additionally, it was shown that the perfect bond assumption was sufficiently safe for the design of the GFRP RC slabs.