方形钢管约束下核芯混凝土的本构关系

分析了方形钢管混凝土在轴压下的受力机理，将钢管对混凝土的约束作用等效为有效侧向应力，借鉴典型的约束混凝土本构模型，提出了方形钢管约束的核芯混凝土的等效单轴受压本构关系。基于试验结果，讨论确定了所提出的本构关系的几个关键参数和强度指标，即峰值应变修正系数、钢管有效侧向压应力系数、峰值时钢管的横向应力等。采用建议的本构关系计算了轴压下方形钢管混凝土短柱的荷载－应变全过程曲线，计算结果与试验结果吻合良好。建议的本构关系可以用于评估方形钢管混凝土短柱的极限承载力和延性。

CONSTITUTIVE RELATIONSHIP OF SQUARE CFT

A constitutive relationship of concrete core confined by square steel tube is put forward based on the analysis on interaction mechanics within components of square CFT and the conception of equivalent lateral compressive stress. The constitutive relationship takes similar form of the constitutive model of confined concrete while its parameters such as coefficient of ultimate strain, effectively lateral compressive stress, and transverse stress of steel tube and so on are modified to fit square CFT with experimental results. Finally, the experimental specimens are calculated with the proposed constitutive relationship and the theoretical calculating load-strain curves are shown in good agreement with the experimental ones. The proposed constitutive relationship can evaluate ultimate strength and deformation of square CFT effectively.