Effect of Cracks Along the Rebars on the Bond Deterioration Under Tensile Stress in Reinforced Concrete

The mechanical interaction, namely the bond between concrete and rebar plays an important role in the formation of the load-bearing mechanism. When the rebar corrodes, the bond will deteriorate because of cross-section loss, contact loss, and corrosion crack. This research aimed to clarify the effect of corrosion cracks on bond under tensile stress through pull-out tests and numerical analysis. To focus only on the effects of corrosion crack, a smooth steel plate was placed as an artificial crack along the main reinforcing bar. The pull-out test results showed that artificial cracks deteriorated the bond and that the number of cracks affected the degree of deterioration. It was also observed that different deterioration mechanisms were also observed depending on the relative position of the cracks to the lugs. To investigate the microscopic mechanism, a finite element analysis was performed to accurately represent the lug shape. The analytical study revealed the mechanism and the effects of different lug angles on the bond mechanism. The lug angle affected the stress transfer state to the concrete around the rebar. Experimental and analytical investigations showed that due to corrosion crack, the local bearing capacity of the mechanical interlock apparently deteriorated. In addition to these factors, it was also confirmed that lug angle and crack location had an influence on bond.