Polyethylene terephthalate (PET) fiber-reinforced polymer (FRP) composites, which is a kind of low-carbon production and have a large rupture strain, may have prosperous application outlooks. PET FRP wrap has been explored as confining reinforcement for concrete, and the majority of investigations are limited to PET FRP-confined concrete in circular and square columns, whereas PET FRP-confined rectangular columns have barely been touched. To fill this research gap and gain a fundamental understanding of the confinement mechanism, comprehensive compressive tests on 36 columns were conducted in this study, in which the confinement thickness, cross-section aspect ratio, and specimen size were the focal points. All specimens exhibited a three-segment behavior (i.e., strain hardening-softening-hardening response). In addition, it is demonstrated that specimen size had an insignificant effect on the axial stress-strain response of small and medium columns with a height less than 400 mm, provided that their confinement levels were the same (or similar). Furthermore, the minimum effective confinement stiffness for PET FRP-confined rectangular columns to achieve sufficient confinement was 0.004, which was extracted from all available test results. A design-oriented model with improved performance was proposed and the simulated full axial stress-strain showed close agreements with the test results.

聚对苯二甲酸乙二醇酯（PET）纤维增强聚合物（FRP）复合材料属于低碳生产，断裂应变大，具有广阔的应用前景。PET FRP 包裹已被探索作为混凝土的约束钢筋，大多数研究仅限于圆形和方柱中的 PET FRP 约束混凝土，而几乎没有触及 PET FRP 约束矩形柱。为了填补这一研究空白并从根本上了解约束机制，本研究对 36 根柱进行了综合压缩试验，其中约束厚度、截面纵横比和试件尺寸是重点。所有标本都表现出三段行为（即应变硬化-软化-硬化反应）。此外，结果表明，试件尺寸对高度小于 400 mm 的中小型柱的轴向应力-应变响应影响不大，前提是它们的约束水平相同（或相似）。此外，PET FRP 约束矩形柱实现充分约束的最小有效约束刚度为 0.004，这是从所有可用的测试结果中提取的。提出了一种性能改进的面向设计的模型，模拟的全轴向应力-应变与试验结果非常吻合。PET FRP 约束矩形柱实现充分约束的最小有效约束刚度为 0.004，这是从所有可用的测试结果中提取的。提出了一种性能改进的面向设计的模型，模拟的全轴向应力-应变与试验结果非常吻合。PET FRP 约束矩形柱实现充分约束的最小有效约束刚度为 0.004，这是从所有可用的测试结果中提取的。提出了一种性能改进的面向设计的模型，模拟的全轴向应力-应变与试验结果非常吻合。