2021 Volume 21 Issue 5 Pages 5_58-5_78
To improve the repairability of reinforced concrete (RC) buildings after an earthquake, it is desirable that the damage area of the members be small. One method to control the damage area is de-bonding of longitudinal rebars. The de-bonding of longitudinal rebars can suppress the damage area of an RC beam member, but the strength and energy dissipation performance are lower than those of a normal beam member. In this study, to suppress the damage area and secure the restoring force characteristics, the structural behavior under antisymmetric bending of RC beam with a guaranteed hinge position having de-bonding of longitudinal rebars and its anchoring at the center of the span was examined. First, finite-element analyses of the RC beam member with the parameters of the de-bonding position of the longitudinal rebars, the anchoring method of the longitudinal rebars at the center of the span, and the presence or absence of the slab were conducted. The analysis demonstrated that restoring force characteristics equivalent to those of a normal beam can be secured and the damage area can be suppressed by de-bonding of the longitudinal rebars only at the four corners, along with anchoring with a steel plate at the center of the span. Next, a cyclic loading test of an RC beam with a slab manufactured using that de-bonding and anchoring method was conducted. The test confirmed the stable restoring force characteristics. In addition, cracks were concentrated at the assumed hinge position, and the damage area could be suppressed. The maximum residual crack width of the beam was small enough that the building could continue to be used with minor repairs.
