Experimental, analytical and numerical assessment of the bond-slip behaviour in concrete-filled-FRP tubes

摘要

The interfacial bond between the fiber-reinforced polymers tube (FRP-T) and its concrete core (CC) is necessary to transfer the loads from the FRP-T to the CC. In this study authors present an experimental investigation of the interfacial bond strength between the circular pultruded FRP-Ts (with or without sand-coating) and a CC. It also aims to evaluate the use of sand-coating as a bond enhancer to improve the interfacial bond strength of the concrete filled FRP tube members. Twelve (12) full-scale circular CFFT specimens with 200 mm length and 12,7 mm wall thickness were tested, with two different diameters (305 mm and 406 mm) and two different inner surface texture (sand-coated or not). The driving force and the slippage between the FRP-T and its CC were captured to plot the interfacial bond-slip relationships for each specimen. The experimental results showed that the measured interfacial bond stress between the pultruded FRP-T and its CC (without sand-coating) was varying from 0.022 MPa to 0.028 MPa then could therefore be neglected. Meanwhile, the interfacial bond strength of the same tube with sand-coating was varying from 0.43 MPa to 1.00 MPa. Consequently, sand-coating as a bond enhancer was proven to significantly improve the interfacial bond strength of the pultruded FRP-T. This paper also presents results from an analytical model and a F.E. simulation model of the interfacial bond-slip behaviour for CFFT members. Coulomb stick-slip friction model is used to characterise the interfacial connection behaviour between the FRP-T and its CC. Experimental, analytical and numerical results are consistent.