STUDY ON BEHAVIOR OF RESTORING BAR AND INCREASING OF FATIGUE LIFE UNDER CYCLIC LOADING AFTER CRACK REPAIRING

Abstract

 Tensile test of reinforced concrete members with crack repairing under cyclic loading was conducted to clarify their basic characteristics. When the maintained tensile stress of the reinforcing bar during the crack repairing is different, the residual strain of the reinforcing bar at unloading becomes larger according to amplitude of its tensile stress. In case of using the epoxy resin as the repairing material under the larger tensile force, the bond force of the bar near the repaired crack was recovered. When using cement based repairing material instead of epoxy resin, the influence on a strain behavior of the reinforcing bar does not show a large difference.
 A prediction equation to the residual strain of the reinforcing bar after crack repairing was proposed from maximum strain for the cyclic load hysteresis and the maintained strain of the reinforcing bar at crack repairing. It was shown that, increasing the residual stress at unloading generated the moderate pre-stress force to the reinforcing bar, and thus prolonging the fatigue life of the reinforcing bar by reducing the stress amplitude under the cyclic loading.