Mechanical Properties Of FRP Bar-ECC-Concrete Composite Structures

Fibre-reinforced polymer (FRP) bar is a promising material to overcome the corrosion issue of conventional reinforced concrete (RC) structure due to its high strength-to-weight ratio and excellent corrosion resistance. Engineered cementitious composite (ECC) is a new generation of high performance fibre reinforced concrete with the characteristics of high ductility. The test result showed that ECC has an ultimate strain exceeding2%and a self-controlled micro-crack capability with a fiber volume fraction of2.0%. When ECC and FRP bar are combined together by taking their respective advantages, the composite displays a good capacity for crack resistance and an excerllent tensile performance. To understand the mechanical properties of FRP bar-ECC-concrete composite structure, the finite element method was adopted to analyze the bond behavior between BFRP bar and ECC and the mechanical properties of FRP bar-ECC-concrete composited beams, and experiment was carried out to investigate the performances of CFRP bar-ECC strengthed RC columns under eccentric compression. The detailed work in this study can be summarized as follows:(1) The constitutive modes to describe the relationship between BFRP bar and ECC were put forward by the comparision of existing models and test results.(2) A finite element model was established, in which the nonlinear nodal springs were used to model the adhesion behaviors, to discuss the bond-slip relationship between FRP bar and ECC. Meanwhile, the development length of embedment was obtained on basis of the continuous curve model.(3) The three-dimensional finite element model of ECC-concrete-FRP bar composited beam was established to analyze the mechanical properties under the flexural load. The comparision results between experimental and numerical results showed that the finite element was validated and reliable. Furthermore, a series of sensitivity analyses were conducted to display the effects of the ECC thickness, the FRP bars ratio and the concrete strength on the properties of the composite beams.(4) Experiments were conducted to study the effectiveness of strengthening the RC columns with FRP bar and ECC composite. Then, finite element models were established to investigate the responses of strengthened columns under eccentric compression. Comparisons show that the numerical results are in a good agreement with the test data.