HYSTERETIC BEHAVIOR OF SELF-CENTERING ROCKING STEEL FRAME STRUCTURE WITH LIFTING IN THE MIDDLE OF COLUMN

A novel self-centering rocking steel frame with lifting in the middle of column (SCRSF-LMC) is proposed to enhance the recovery capability and seismic performance of the self-centering rocking steel frame with column base lifting (SCRSF-CBL). The rocking joint of SCRSF-LMC is located in the middle of the bottom column and utilizes replaceable web-hourglass-shaped steel pins (WHPs) as energy dissipation elements. To investigate the hysteretic behavior of SCRSF-LMC, a quasi-static test was conducted on a three-story, single-span SCRSF-LMC specimen. Subsequently, a multi-scale finite element model of the specimen was established by using the finite element software ABAQUS and its accuracy was verified. Nineteen finite element models were established to analyze the impact of key design parameters on the hysteretic behavior of the self-centering rock steel frame. The results indicate that SCRSF-LMC, through the uplifting and self-centering mechanism of the rocking joint, concentrates structural damage on the replaceable WHPs, with other components remaining elastic and exhibiting negligible residual deformation under a roof drift ratio of 2.5%. Compared with SCRSF-CBL, SCRSF-LMC demonstrates higher initial stiffness, post-yield stiffness, load-bearing capacity, deformation capacity and energy dissipation capability. The change of rocking joint position has no effect on the deformation mode of the self-centering rocking steel frame. The initial prestress of steel strands significantly affects the initial stiffness, load-bearing capacity, self-centering capability and relative energy dissipation ratio of SCRSF-LMC but has no impact on single-loop energy dissipation or post-yield stiffness. The number, length and diameter of WHP steel pins do not affect the initial stiffness and uplift force of the rocking frame in SCRSF-LMC, but significantly influence post-yield stiffness, ultimate load-bearing capacity, single-loop energy dissipation and relative energy dissipation ratio. To avoid the global uplift of SCRSF-LMC and ensure good self-centering and energy dissipation performance in practical applications, the self-centering rate should be between 1.0 and 1.5.