钢管混凝土箱形叠合柱抗震性能试验研究

Experimental study on seismic performance of CFST reinforced concrete column with hollow box section

为研究钢管混凝土箱形叠合柱(简称CFST箱形叠合柱)的抗震性能,以面内柱肢间距和轴压比为参数,进行了5个CFST箱形叠合柱试件和1个CFST格构柱试件的拟静力试验。研究结果表明:水平低周反复荷载作用下,CFST箱形叠合柱的荷载-位移滞回曲线呈捏拢状,主要破坏形式表现为面外方向外包混凝土的水平裂缝、面内方向腹板的斜向裂缝、柱肢底部外包混凝土的竖向裂缝及压溃;CFST箱形叠合柱受力全过程可分为弹性阶段、可修复阶段、刚度劣化阶段、承载力劣化阶段和剩余承载力阶段,在部分柱肢外包混凝土退出工作后,CFST箱形叠合柱的承载力有较大幅度下降,但CFST格构柱骨架仍可继续抵抗水平荷载作用。面内柱肢间距从500 mm增至650 mm时,弹性刚度、水平承载力和累积滞回耗能分别增大了44.6%、26.0%和15.8%。轴压比从0.10增至0.20时,水平承载力和累积滞回耗能分别增大了33.7%和48.7%。通过柱底塑性铰截面应力状态的理论分析,提出了有较高精度的CFST箱形叠合柱水平承载力计算方法,计算结果与试验结果吻合较好。

The quasi-static tests of five concrete filled steel tube(CFST) reinforced concrete columns with hollow box section(CFSTRC-HBS columns for short) and one CFST lattice column were conducted to investigate the effect of in-plane limb spacing and axial compression ratio on the seismic performance of CFSTRC-HBS columns. The results indicate that CFSTRC-HBS columns exhibit pinch-shaped load-displacement hysteretic curves under horizontal reversed loading and the main failure modes are manifested as the horizontal cracks of outer concrete in the out-of-plane direction, the diagonal cracks of in-plane concrete web, and the vertical cracks and crushing of outer concrete at the column bottom. The whole loading process can be divided into elastic stage, repairable stage, stiffness degradation stage, bearing capacity degradation stage and residual bearing capacity stage. After the partial outer concrete is damaged and fails, the bearing capacity of CFSTRC-HBS columns decreases significantly, but the CFST lattice skeleton can continue to resist horizontal load. When the in-plane limb spacing increases from 500 mm to 650 mm, the elastic stiffness, the horizontal bearing capacity, and the cumulative energy dissipation increase by 44.6%, 26.0%, and 15.8% respectively. When the axial compression ratio increases from 0.10 to 0.20, the horizontal bearing capacity and the cumulative energy dissipation increase by 33.7% and 48.7%, respectively. Based on the theoretical analysis of the stress state of the plastic hinge section at the bottom of the column, the calculation method of the horizontal bearing capacity of CFSTRC-HBS columns with high precision is proposed, which is in good agreement with the test results.