Flexural Stiffness Of Rectangulareinforced Concrete Beams Strengthened With Externally Bonded Cfrp Sheets

Strengthening reinforced concrete structure with externally-bonded steel plate, glass fiber, carbon fiber, steel mesh and so on, which is a simple and convenient method in direct reinforcement, is widely applied to engineering in recent years, especially carbon fiber is the focus of research and application.This study investigates the flexural stiffness of rectangular beams strengthened with externally bonded carbon fiber sheets. Twelve same rectangle section rectangular beams were constructed, four contrast beams, four strengthened beams with two carbon fiber sheets and four strengthened beams with three carbon fiber sheets. Main considered in strengthening ratio. All these strengthened rectangular beams are statically loaded under third-point bending. Structural testing of the beams shows that carbon fiber strengthening can highly increase flexural stiffness.A formula for calculating the short-term stiffness of reinforced concrete beams strengthened with carbon fiber has been established on the basis of analyzing the law of changes in the sectional stiffness of these beams and through a statistical analysis of the test data. The formula has a higher precision.