柱端带肋方钢管混凝土柱抗震耗能分析

Seismic energy dissipation analysis of concrete-filled square steel tubular columns with stiffeners at column ends

方钢管混凝土柱在高层及超高层中得到了广泛应用,但存在钢管对混凝土约束较弱与柱端部局部屈曲等问题,有必要采取构造措施以提高柱的抗震性能。通过建立端部带肋方钢管混凝土柱的三维实体精细有限元模型并与拟静力试验结果验证,有限元结果与试验结果吻合良好,之后建立多个足尺模型进行参数分析,分析了柱端设肋对钢管水平鼓曲与竖向位移、钢管与混凝土的应力-应变、塑性耗能的影响,探讨了不同肋高下柱的塑性耗能分配机制。结果表明:柱端设置加劲肋可显著减少柱的水平鼓曲和竖向位移,提高柱的峰值承载力和延性,减小钢管与混凝土的压应变并提高压应力,增大柱的总塑性耗能值,延缓柱的破坏;轴压比为0.5、0.8时,当肋高分别达到1000mm、1500mm,再增大肋高对柱的塑性耗能影响较小。研究结论可为实际工程中柱端带肋方钢管混凝土柱的设计与加固构造措施提供参考与依据。

Concrete filled square steel tubular columns have been widely used in high-rise and super high-rise buildings,but there are some problems,such as weak constraint of steel tubes on concrete and local buckling of column ends.It is necessary to take structural measures to improve the seismic performance of columns.By establishing a three-dimensional solid fine finite element model of concrete-filled square steel tubular column with ribs at the end and verifying it with the pseudo static test results,the finite element results are in good agreement with the test results.Then,several full-scale models were established for parameter analysis,the effects of ribs at the end of the column on the lateral buckling and vertical displacement of the steel tube,the stress-strain and plastic energy consumption of the steel tube and concrete were analyzed,and the plastic energy consumption distribution mechanism of the column under different rib heights is discussed.The results show that the setting of stiffeners at the end of the column can significantly reduce the horizontal buckling and vertical displacement of the column,improve the peak bearing capacity and ductility of the column,reduce the compressive strain between steel tube and concrete and increase the compressive stress,increase the total plastic energy consumption of the column,and delay the failure of the column.When the axial compression ratio is 0.5 and 0.8,when the rib height reaches 1000mm and 1500mm respectively,continue to increase the height of the rib has little effect on the plastic energy consumption of the column.The research conclusions can provide reference and basis for the design and reinforcement structural measures of concrete-filled square steel tubular columns with ribs at the end of columns in practical projects.