Empirical and NLFEA prediction of bond-slip behavior between DSSF concrete and anchored CFRP composites

Abstract

A precise bond-slip model between discontinuous structural synthetic fibers (DSSF) concrete and anchored carbon fiber reinforced polymer (CFRP) is of primary importance in the reaching the ultimate strength of CFRP composites as well as the modeling of Reinforced concrete (RC) structures strengthened with CFRP composites. In this paper, a new bond slip model is proposed in terms of DSSF content (0, 3, and 5 kg/m3 equivalent to fiber volume fractions (Vf) of 0%, 0.33%, and 0.55%, respectively), CFRP bonded length (Lf) (50, 75, and 100 mm), CFRP bonded width (bf) (50, 75, and 100 mm), and anchored system (with and without a CFRP anchoring strip width (bfA) of 25 mm and length (LfA) of 150 mm). This proposed model is then assessed using experimental test results on anchored CFRP-DSSF concrete bonded blocks subjected to double-shear pull-off test, existing bond-slip models in the literature, and database of pull tests published by several researchers. After that, the anchored CFRP-DSSF concrete bonded blocks were modeled and analyzed using nonlinear finite element analysis (NLFEA). After realistic validation with the experimental test results, NLFEA was expanded to proposed an expression for the influence of anchored CFRP sheet in terms of bfA (25, 50, 75, and 100 mm) and LfA (100, 125, and 150 mm) on the proposed bond-slip model. The special characteristic of the present study is that the new proposed bond-slip model is based on anchored CFRP composite and DSSF concrete; instead, the existing bond-slip models are based on CFRP composite without anchorage and ordinary concrete. Finally, the proposed bond-slip model is provided an accurate prediction of the large test database of bond strength and corresponding slippage.