带肋薄壁复式钢管混凝土柱的抗震性能研究

Seismic behaviour of concrete-filled thin-walled double-tubular columns with longitudinal stiffeners

带肋薄壁复式钢管混凝土柱具有较好的耐火性能和经济性,同时钢管混凝土构件多用于地震频发区域,因此有必要研究其抗震性能。以轴压比和内管外径为主要参数,进行了6根带肋薄壁复式钢管混凝土压弯柱的低周反复加载试验。试验结果表明:该类组合柱的滞回曲线饱满,具有良好的抗震性能,其承载能力和耗能能力明显高于带肋薄壁钢管混凝土对比柱;该类柱均为面内压弯破坏;随着轴压比的增大,试件的延性、累积耗能随之减小,后期刚度退化加剧;随着内管外径的增大,试件的承载力、延性和耗能能力提高,但内管外径对刚度退化的影响较小。建立了带肋薄壁复式钢管混凝土柱的有限元模型,并利用试验结果检验了模型的准确性。基于该模型开展参数分析,结果表明钢管屈服强度、外部混凝土强度、轴压比、径宽比、径厚比和长细比等参数对该类构件的承载力影响较显著。最后基于参数分析,建议了荷载-挠度恢复力模型。

Concrete-filled thin-walled double-tubular(CFTDT)columns with longitudinal stiffeners have high fire resistance and economy.Meanwhile,the concrete-filled steel tubular members are widely used in earthquake prone areas.Thus,it is necessary to study its seismic performance.Hysteretic tests of six CFTDT columns with longitudinal stiffeners were conducted.Main parameters include the axial compression ratio and the outer diameter of outer steel tube.The test results show that the hysteretic loops of the composite columns are stable and the seismic behaviors are good,meanwhile the bearing capacity and energy dissipation capacity of the composite columns are significantly higher than those of the concrete-filled cold-formed thin-walled steel tubular counterpart with longitudinal stiffeners;The failure mode of the specimens is combined compressive and in-plane bending failure;as the axial compression ratio of the specimen increases,the ductility and energy dissipation capacity decrease,and the rate of stiffness degradation also accelerates significantly;as the outer diameter of outer steel tube of the specimen increases,the strength,ductility and energy dissipation capacity increase.However,the outer diameter of outer steel tube has slight effect on the stiffness degradation.The nonlinear finite element(FE)model of the CFTDT columns was developed and verified by test results.Based on this FE model,the parametric analysis was conducted.The parameters including the yield strength of steel tubes,the outer concrete strength,the axial load ratio,the diameter to width ratio,the diameter to thickness ratio and the slenderness ratio have significant influences on the bearing capacity of the composite columns.Based on the parametric analysis,the load-deflection restoring force model was finally proposed for composite columns.