Effects of simultaneous fatigue loading and corrosion on the behavior of reinforced beams

This paper investigated experimentally the behavior of reinforced concrete (RC) beams under simultaneous fatigue loading and steel corrosion. Fourteen specimens were manufactured and tested under four-point bending fatigue loading, during which reinforcement corrosion was induced by an accelerated method using a 5% NaCl solution combined with a constant impressed current. Four different levels of maximum fatigue loads, namely 50%, 55%, 65% and 75% of ultimate loading capacity with fatigue loading frequencies of 1.5 Hz and 4.5 Hz and corrosion impressed currents of 0.5 A, 1.0 A, 1.5 A and 2.5 A were applied to the beams. Crack patterns, failure modes, fatigue life, reinforcement corrosion, and flexural stiffness were investigated. Test results indicated that the inclusion of corrosion significantly decreased the ductility, fatigue life and flexural stiffness of the RC beams. Greater levels of maximum fatigue loads and impressed current tended to shorten fatigue life. General and local corrosion occurred simultaneously under the joint effects of fatigue loading and corrosion. It was also found that the flexural stiffness of RC beams under coupled fatigue loading and corrosion increased in early loading cycles and then remained approximately stable, followed by a rapid decrease just prior to failure.