Investigation Of Concrete Beams Locally Strengthened With External CFRP Tendons

Fiber Reinforced Polymer(FRP) tendon, a new advanced composite material, has many advantages such as lightweight,high strength,corrosive resistance, fatigue resistance,and so on。FRP tendons can do well with the corrosive problem of reinforcing steel bar in the concrect structure. FRP tendon is a well kind of prestressed material.The study is sustained by"Beijing Municipal Science & Technology Funding Item(NO.805001)"and"Beijing Municipal Education Funding Item(NO. KM200610005007)". Based on the domestic and international study,a new locally strengthening method of concrect structure with external prestressed tendons is put forword. It is presented that how to fix on the critical distance. The Formula of ultimate flexural capacity is given according to Plastic Principle. Five prestressed concrete testing beams were designed with different reinforcing distance. Based on experiments of FRP prestressed concrete beams, failure pattern,load-deflectioncurve,stress increasing and so on are studied systematically. Influence of the reinforcing distance on reinforcing effect is analysed. The results of the experiment are compared with calculated flexural capacity. And a nonlinear analysis of concrete beams on the basis of ANSYS program is used in order to overcome the shortcomings of experiments。The results indicate that locally strengthened technique has good reinforcing effect. It can improve the crack load, yield load and limiting load. The more the reinforcing distance increace, the better the improvement is. Defection in midspan of beam will minish as the reinforcing distance increasing. The rational reinforcing distance is very important to modes of failure. When the diatance is too much, failure mode is brittle. The calculated flexural capacity has good agreement with the test risult. The locally strengthened technique shows a new method to continuous reinforced concrete beam strengthened.