矩形钢套筒约束混凝土轴心受压应力应变关系

进行了6个矩形钢套筒约束混凝土试件的轴心受压试验，试验结果表明：矩形钢套筒能够对其内部混凝土形成有效约束，显著提高混凝土受压峰值应力，使约束混凝土受压应力应变曲线的下降段更加平缓，有效改善混凝土的极限变形能力。在试验的基础上，通过对试验中钢套筒的应变和钢套筒内混凝土的受力状态进行分析，给出了矩形钢套筒对混凝土横向有效约束力的计算方法，借用Mander模型，进一步提出了受约束混凝土单轴受压应力应变计算模型。将计算模型与试验的钢套筒约束混凝土应力应变曲线进行对比，二者吻合良好。

Stress-strain relationship of rectangle steel tube confined concrete under axial compression

Six rectangle steel tube confined concrete columns were investigated experimentally under axial compression. The experimental results show that:The rectangle steel tube can effectively confine internal concrete and obviously improve the peak stress. In addition, the descending branch of confined concrete stress-strain curve is gentler and the ultimate deformation ability of concrete is improved effectively. On the basis of experiments, a method to calculate the effective transverse confined stress provided by the rectangle steel tube was proposed through analyzing the strain of steel tubes and the stress state of core zone concrete. Furthermore, a model to determinate the stress-strain relationship of rectangle steel tube confined concrete under axial compression was put forward reference to the Mander''s model. Computation results of the stress-strain curve of rectangle steel tube confined concrete were in good agreement with the experimental results.