Experimental Study on Fatigue Stiffness of RC Beams Strengthened with CFL under Variable Amplitude Overloading

Abstract

This paper study the effects of stress amplitude on the fatigue performance of reinforced concrete (RC) beams strengthened with carbon fibre laminate (CFL). A total of 15 spcimens were tested under three point bending. Three load levels over 60% bending capacity of the strengthened beams with a stress ratio of 0.1 were applied to three groups of five specimens, respectively. The stress amplitudes of groups 2 and 3 are 10% and 15% larger than group 1, respectively. The loads and deflections during the tests were recorded. The fatigue stiffness of the strengthened RC beams with variable stress amplitude was discussed. The experimental results show that the rates of the bending stiffness deterioration of the retrofitted beams, which increase with the load level, under constant fatigue loading are smaller than those under variable fatigue loading.