Cyclic stress–strain behavior of low-diameter reinforcing bars for thin concrete walls

During seismic events, cyclic demands exceeding the elastic limit load and buckling of steel reinforcing bars significantly impact the global response of thin and lightly reinforced concrete (TLRCW) wall buildings. This study evaluates the cyclic response of low-diameter steel reinforcing bars commonly used in thin RC walls. The experimental program of the study comprises the characterization and reversed cyclic tests of 60 specimens obtained from steel reinforcing bars grade 60 (420 MPa) with nominal diameters of 9.5 and 12.7 mm. An increasing, symmetrical strain protocol was used during the cyclic tests. The study analyses the stress–strain curves obtained in the cyclic tests of steel reinforcing bars and assesses the effect of parameters such as the slenderness ratio, bar diameter, and yield stress on the cyclic response of bars. The onset of buckling and its effects on the cyclic response of steel reinforcing bars, such as pinching and stress reduction in compression are also examined. The degradation of the mechanical properties of steel reinforcing bars obtained during cyclic tests was evaluated and compared to that obtained during monotonic tests. The study shows that low-diameter steel rebars under cyclic loading exhibit lower ductility and premature hardening in tension when compared to bars subjected to monotonic loading. Finally, fundamental properties of low-diameter steel reinforcing bars subjected to cyclic loads were established, such as ductility and hardening capacity. These properties will contribute to enhancing the understanding of the seismic behavior of TLRCW buildings.