Abstract: Based on the accelerated corrosion test and the fatigue loading test of thirteen reinforced concrete beam
specimens，the failure mode and flexural stiffness of corroded reinforced concrete (RC) beams under fatigue loads are investigated． The test results show that，after cyclic loading a certain number of times，fatigue failure occurs in all the corroded beam specimens and it is marked by the fatigue fracture of a main reinforcing bar，and that，nofatigue failure occurs in uncorroded specimens after cyclic loading two million times，and the fatigue effect has no substantial influence on the static failure mode and the ultimate bearing capacity of uncorroded RC beams． Moreover，analysis on the flexural stiffness change of corroded ＲC beams under the effect of the fatigue loading indicates that there are two obvious stages，specifically，the flexural stiffness decreases slowly and then tends to be stable．According to the measured data，the stiffness correction coefficients，which take into account the steel bar corrosion and the fatigue effect respectively，are introduced to quantitatively derive the correction formula calculating the flexural stiffness of the corroded RC beams under the fatigue loading，and the formula is then verified by comparing
the calculated values with the measured ones． It is also found that the proposed formula can be used to calculate and evaluate the deflection of corroded ＲC girder bridges under long-term live loads．

Key words:  corroded reinforced concrete beams, flexural stiffness, corrosion fatigue, fatigue loading, deflection