ひび割れ誘発材に異形鉄筋を用いたRC造耐震壁に関する曲げ実験および解析的研究

Seismic performance of flexure-dominant reinforced concrete walls with deformed bars at crack control joints as crack inducers is experimentally and numerically investigated. Deformed-bar-crack-inducers have been proposed for use in structural walls in mid-to-high-rise housing complexes.A couple of half-scale two-story RC wall test specimens were constructed on a stiff base foundation. They had boundary columns at both sides with a stiff girder at the top for loading. The wall in each story was 1100 mm high, 2200 mm long, and 100 mm thick. The thickness was reduced to 80 mm at the crack control joints, two of which were located at the boundary between wall and columns, and one of which was at the mid-span. The test parameter was the diameter of the crack-inducing bars; type D6 for test specimen FWP63R07 and type D16 for FWP63R20. The nominal compressive strength of concrete in design was 30 MPa and longitudinal reinforcements of the beams and columns were type SD345. The other reinforcing bars were type SD295A. To design the walls not to fail in shear, the ultimate shear strength of the walls was 1.91 times greater than the ultimate flexural capacity without considering the reduction in the wall thickness at the crack control joints. While the two boundary columns were subjected to 1080 kN as the axial load, the lateral loading was applied at the mid-span of the top beam.By using the finite element analysis program DIANA9.6, a detailed numerical study on the structural response of the walls such as load-drift angle relationship, stress-strain distribution of the crack-inducing bars, stress distribution of the deformed bars, and the vertical displacements of the boundary columns' bases was carried out as well.The following conclusions can be drawn from the experimental and numerical works of this study.(1) The crack-control joints at the boundary columns' faces did not contribute to the overall collapse mechanism.(2) At drift angel by 0.5% the two test specimens exhibited identical load-deflection relationships. No influence of shrinkage cracks and bar diameters were found.(3) The test specimen with type D6 crack-inducing bar reached its ultimate strength at R=1.5% while the other test specimen with larger crack-inducing bar diameter (type D16) exhibited its ultimate strength at R=1.0%. It seems that the difference in crack-inducing bar diameter could contribute to such a discrepancy.(4) It was found that the crack-inducing bar diameter had no influence on