Abstract:Steel tubes are used to constrain traditional reinforced concrete (RC) columns, forming steeltube-reinforced concrete (STRC) columns, which exhibit superior load-bearing capacity and energydissipation performance. However, when applied to frame joint design, the joint area still adopts ordi-nary RC column node structures, potentially leading to weak points without steel tube constraints,making the joint area prone to damage. To address the issue of weak seismic performance at the jointsof STRC columns, an enhancement method using built-in short steel columns was proposed. Finite el-ement models of joint specimens with the same construction form were established based on theABAQUS working platform and the numerical results for failure modes, hysteresis curves, and steel stress were compared with test results, showing good agreement. On this basis, the influence of thebuilt-in steel length and axial compression ratio on the seismic performance of the joints was discussed.The results indicated that with the increasing length of the built-in steel, the load-bearing capacity, ul-timate displacement, and ductility of the specimens were improved to varying degrees, while the axialcompression ratio had a minor effect on the mechanical properties of the specimens. Through furtheranalysis of the failure mechanism, bending resistance, and energy dissipation capacity of the built-insection steel, suggestions for the optimal length of the built-in section steel to meet the seismic perfor-mance requirements of the joint were proposed.
