圆端形椭圆钢管约束混凝土本构关系等效方法和轴压性能研究

Study on equivalent constitutive relation and axial compressive behavior of round-ended elliptical concrete-filled steel tube columns

目前国内外对圆端形椭圆钢管混凝土柱的受力性能研究尚不系统,缺乏合理的圆端形椭圆钢管约束核心混凝土本构关系模型。为了解决核心混凝土本构关系问题,文章提出一种计算圆端形椭圆钢管约束核心混凝土本构关系的简化等效方法,用试验结果验证了该方法的可行性和准确性。采用ABAQUS有限元程序建立了圆端形椭圆钢管混凝土轴压短柱的数值分析模型,研究了诸多参数对圆端形椭圆钢管混凝土轴压承载力的影响,揭示了圆端形椭圆钢管混凝土短柱的破坏模式和受力机理。研究结果表明:圆端形椭圆钢管混凝土短柱在轴压作用下的破坏模式主要包括中部鼓曲破坏、端部鼓曲破坏和多带鼓曲破坏;其轴压受力特征均与约束效应系数有关;圆端形椭圆钢管混凝土短柱的轴压极限承载力随混凝土强度、钢材强度及截面尺寸的增大而增大。研究结果可为圆端形椭圆钢管混凝土柱理论研究和工程应用提供参考。

At present, the research on the mechanical behavior of round-ended elliptical concrete-filled steel tube(RECFST) columns is not systematic, and the reasonable constitutive relation model of confined core concrete is still lacking. To solve the problem of constitutive relation of confined core concrete, a simplified equivalent method for calculating constitutive relation of confined core concrete was proposed. The feasibility and accuracy of the equivalent method were verified by test results. In addition, the numerical analysis model of RECFST columns under axial compressive loading was established by ABAQUS software. The effect of various parameters on the axial compressive capacity of RECFST was analyzed. Failure modes and mechanical mechanism were also investigated. The results showed that the failure modes of RECFST columns included middle-height buckling, end local buckling and multi-ribbon buckling. The ultimate axial compressive capacity of RECFST columns increased with the increase of concrete strength, steel strength and sectional area. The results of the study will provide reference for the theoretical study and engineering application of RECFST columns.