约束混凝土本构模型的下降段影响着钢管混凝土的力学性能预测,结合6组方钢管混凝土短柱轴压破坏试验结果,提出一种软化特征可控的双参指数型约束混凝土本构。双参指数型本构考虑了方钢管宽厚比、混凝土强度、钢管截面含钢率等因素的影响,能够很好地模拟在不同约束条件下混凝土的软化行为。基于双参指数型本构,对6组方钢管混凝土试验结果进行了轴压破坏的受力全过程模拟,计算结果和试验结果吻合良好。
The softening characteristic of the constitutive model for confined concrete is vital for predicting the behavior of Concrete Filled steel Tube (CFT) columns. Based on 6 groups of experimental results for square CFTs under uniaxial compression, a two-parameter exponential constitutive model is proposed to depict the softening behavior of confined concrete. The width-to-thickness ratio, concrete strength and steel strength etc. of square CFTs are considered in the proposed constitutive model which simulates the softening behavior of confined concrete under different loading condition well. Based on the proposed confined concrete constitutive model, the overall failure process of 6 groups of square CFTs under uniaxial compression is calculated. The calculation results match the test reasonably.