EXPERIMENTAL STUDY ON THE MECHANICAL PROPERTY OF STEEL BAR-PIERCED JOINTS OF RC BEAMS AND RECTANGULAR CONCRETE-FILLED STEEL TUBULAR COLUMNS

To overcome the problems of RC beam-and-rectangular concrete-filled steel tubular column joints in high-rise buildings such as the indirect force transmission, complex construction and unguaranteed construction quality, a steel bar-pierced joint of RC beams and rectangular concrete-filled steel tubular columns was proposed for the Z13 project of the Beijing CBD core area. Low-cycle reciprocating loading tests were performed on the steel bar-pierced joints of RC beams and rectangular concrete-filled steel tubular columns with different reinforcement ratios to study the hysteretic performance, failure mode, energy dissipation capacity and ductility, which were compared with those of the conventional welded bracket joints and the joints of sleeves and brackets for RC beams and rectangular concrete-filled steel tubular columns. Based on the experimental results, the theoretical analysis of the mechanical properties of the steel bar-pierced joints of RC beams and rectangular concrete-filled steel tubular columns was conducted. Practical design formula were derived. It was indicated that the steel bar-pierced joint of RC beams and rectangular concrete-filled steel tubular columns had higher bearing capacity than the other two types of joints, which could meet the structural design requirements of 'strong joints and weak components' and vertical load transmission. They are convenient to construct and reliable in quality. On this basis, the design formula for the bending bearing capacity of the joint is proposed. The section design of the steel corbel section is recommended to bear 80% of the beam end shear force to provide technical support for the optimization of the design of the rectangular concrete-filled steel tubular column-concrete beam through-reinforced joints.