Experimental study on fatigue performance of RC beams strengthened with CFRP under variable amplitude overload and hot-wet environment

Abstract

Highway reinforced concrete (RC) bridges are generally served under hot-wet environment and vehicle overload in south China, which will cause great fatigue damage to the bridge structures. To discuss the fatigue damage mechanism, a fatigue experimental method of RC bridge structures under the coupling action of variable amplitude overload and hot-wet environment was proposed in this paper. Fatigue tests of 38 RC beams strengthened with carbon fiber reinforced polymer (CFRP) were carried out with the experimental method. Fatigue performance and failure mechanism of the beams were discussed. Results showed that bond strength degradation of CFRP-concrete interface under hot-wet environment, early yielding and rupture of tensile rebars under overload, caused the loss of flexural stiffness and fatigue performance of the strengthened beams. Fatigue lives under variable amplitude overload of the strengthened beams were predicted effectively with a proposed modified Miner rule. Both temperature and relative humidity affected the fatigue lives and fatigue limits, while high-temperature and high-humidity environment led to severe deterioration of fatigue performance of the strengthened beams.