Abstract: In order to investigate the flexural behavior of corroded steel beams strengthened with prestressed CFRP sheets under static loading or overloading， the bending tests of seven steel beams were carried out to study the failure mode， bearing capacity and stiffness of the corroded steel beams. The results showed that the CFRP sheets could improve the stiffness and bearing capacity， and adding prestress to the steel beam could remarkably improve the use of CFRP sheets. The corrosion could influence both the stiffness and bearing capacity. The bearing capacity decreased by about 50% when the corrosion degree increased by 1 times. The improvement of the overloading numbers can improve the stiffness by 13% because of the steel’s age hardening， but the bearing capacity can reduce. And the prestress can improve the ductility of the steel beam. The formula of ultimate bearing capacity was established， and the calculated results agreed well with the experimental results.

Key words: overloading, prestressed CFRP sheets, corroded steel beam, age hardening, stiffness