EFFECT OF STIRRUPS ON SEAR FATIGUE LOAD CARRYING MECHANISM OF RC BEAMS WITH REBAR CORROSION CRACKS

Abstract

 The cyclic loading experiments and FE analyses were conducted to make clear the effect of stirrups on shear fatigue load carrying mechanism of RC beams with rebar corrosion cracks. To simulate the most severe state of rebar corrosion cracks, artificial cracks were installed in the beam specimens. As a result of the loading experiments, tied arch mechanism appeared in the beams which had artificial crack tips inside of vertical stress non-contributed region (B-region). No remarkable difference was observed on the load carrying mechanism between sound beams and the beams which had artificial crack tips inside of vertical stress contributed region (D-region). In addition, the dowel action of stirrups was identified from the comparison with the slip displacements on the artificial crack surfaces of the cracked beams with and without stirrups. After the loading experiments, the validity of reproducing method of load carrying mechanism by using artificial cracks was confirmed based on the result of beams which had real corrosion cracks. As a result of decomposition of the load carrying mechanism based on FE analysis, in the beams which had artificial crack tips inside of B-region, the absorbed energy of arch mechanism was decreased by the slip resistance on the artificial crack due to the dowel action of stirrups. It was confirmed that when the absorbed energy of arch mechanism was high, the fatigue life became short regardless of the existence of stirrups and position of the artificial crack tips.