Analysis Of The Ultimate Flexural Capacity Of The Reinforced Concrete Beams Strengthened With Cfrp

Strengthening of concrete structures by bonding Carbon Fiber Reinforced Plastic (CFRP) to concrete surface using epoxy resins has been now recognized to be an effective and convenient method of improving their performance under service loads or to increase their ultimate strength and widely applied in practice. The use of CFRP for this application offers several desirable attributes, such as resistance to corrosion, high strength, light weight. The main advantages of the technique are that the operation can be carried out relatively quickly and simply even when the structure is still in uses. In addition, the resulting changes in member or structure sizes are very small.This paper makes analysis of the ultimate flexural capacity of the RC structure member strengthened by CFRP. At first, the experiment carried out by Tianjin University has been analysed according to the "nonlinear balance trying calculation" method, and the values of yield load and ultimate load agree with the test result better, and the curve of bending moment-curvature, bending moment-deflection can agree with the results. The second, the simplified formula for evaluation the ultimate flexural capacity of CFRP strengthened RC members is presented according to the three probable failure modes (compression failure; CFRP rupture; crushing of the concrete in compression before yielding of the reinforcing steel). It is applicable to both singly and doubly reinforced rectangular sections, as well as flanged sections. Additionally, the direct, general procedure of design is presented, and it is validated by comparisons with results of experiment data available in the literature. At last, finite element analysis (FEA) is done by using software ANSYS, and the FEA results indicates that the CFRP increases the ultimate flexural capacity of the strengthening beam. All these agree with the test results.