圆铝合金管混凝土短柱轴心受压承载力研究

开展了6根圆铝合金管混凝土(简称“CFACT”)短柱的轴心受压承载力试验，套箍系数为0.57~1.26。分析了试件的破坏形态、轴压荷载-轴向应变曲线、截面横向变形系数、峰值荷载和延性。试验结果表明:CFACT轴压短柱发生鼓曲破坏或斜向剪切破坏；其表现出良好的组合效应，具有较高的承载能力与延性。利用ABAQUS有限元软件，结合该文建议的圆铝管约束混凝土的等效受压应力-应变关系和混凝土塑性损伤模型，建立了轴心受压荷载下CFACT短柱的非线性有限元分析模型，并对该模型进行了试验验证。为合理地对CFACT短柱进行设计，讨论和定义了其轴心受压承载力。采用前述有限元模型计算了不同的套箍系数、径厚比、含铝率及材料强度的27根CFACT短柱的轴压承载力。利用试验与有限元分析得到的33根短柱的轴压承载力计算出各柱的截面组合抗压强度。通过分析发现，截面组合抗压强度与混凝土轴心抗压强度之比与套箍系数存在线性关系，进而通过回归分析建立了其组合抗压强度的计算公式。

THE AXIAL STRENGTH OF CONCRETE-FILLED ALUMINUM ALLOY CIRCULAR TUBULAR STUB COLUMNS

To investigate the axial strength of concrete-filled aluminum alloy circular tubular(CFACT)stub columns,six specimens with confinement coefficients of 0.57 to 1.26 were tested under concentric compression.The failure patterns,axial load versus axial strain curves,lateral deformation coefficient,peak load,and ductility were analyzed.The failure patterns included drum-shaped failure and oblique shear failure.The test results show that the columns exhibited a good composite effect between the aluminum tube and core concrete,and had high strength and ductility.An equivalent stress-strain relationship for the core concrete confined by the aluminum tube was proposed for the concrete plastic damage model,and a nonlinear finite element analysis(NFEA)model for CFACT columns was developed using the software ABAQUS.The NFEA model was verified by the test results.To reasonably design the CFACT columns,the axial strength of the CFACT stub columns was discussed and defined.Based on the NFEA model,the axial strengths of twenty-seven columns with different parameters including the confinement coefficient,diameter-thickness ratio,aluminum ratio,and material strength were obtained.Using the acquired axial strengths of thirty-three test and simulated columns,the cross-section composite strength was calculated.The ratio of composite strength to the concrete compressive strength was linearly related to the confinement coefficient.A formula for the composite strength was established by regression analysis.