Nonlinear response analysis of concrete beam reinforced with high performance CF-GF sheet

For the typical concrete beams reinforced with the high performance carbon fiber-glass fiber-Epoxy(CF-GF-EP) sheet, a new three dimensional nonlinear hybrid composite element was studied for the nonlinear performances including stiffness reduction, stress redistribution etc. According to the theory of the solid degradation element, the RC beam was modeled with composite element. Then the contribution matrix of hybrid CF-GF-EP sheet to the new nonlinear hybrid composite element was completed through selective integration technique. The corresponding three-dimensional nonlinear analysis program was developed with the material nonlinearity of the concrete such as Jiang yield criterion, Hinton crushing criterion and Madrid criterion. Compared with the experimental data, the calculated results are in good agreement with the experimental data, which shows the correctness of the nonlinear hybrid composite element and the reliability of the developed program are both testified. The derived hybrid composite element can be accurately used for the whole process of analysis of the beams reinforced with the similar high performance CF-GF-EP sheet. In initial loads, the beams reinforced with the high performance CF-GF-EP sheet have no obvious stiffness reduction and then when the yielding loads and ultimate loads are reached, the stiffness reduction coefficients are about 0.6 and 0.9, respectively. Before cracking loads, the stress of the high performance CF-GF-EP sheet increases slowly and the stress redistribution coefficient of the high performance CF-GF-EP sheet changes little and in the following stage, it increases more rapidly until the structure fails.