Due to the influence of “arching action” in fiber-reinforced polymer (FRP) partially confined concrete columns as a result of the unconfined regions, the confinement of the concrete columns wrapped with discrete FRP strips is less efficient when compared with full wrapping schemes. This study comprehensively investigates the difference of the the confinement mechanism between fully and partially FRP confined circular normal-strength concrete and thus presents a new design-oriented model to predict the stress–strain relationships of partially FRP confined normal-strength concrete. The formulas used to determine the strength and corresponding strain of several key points on the stress–strain curves are also proposed by the regression analysis according to a reliable test database from the relevant literature. Besides, another selected database including 100 FRP partially wrapped circular concrete columns is also collected for model verification. The results show that better performance can be achieved by the new model compared with the selected models in predicting the ultimate conditions of partially FRP confined concrete. Finally, some specimens are chosen to assess the performance of the new model in predicting the complete axial stress–strain curves. The comparisons reveal that satisfactory accuracy and good agreement can be achieved between the theoretical predictions and experimental observations.

中文翻译：

---

部分纤维增强聚合物约束法向混凝土的设计导向轴向应力-应变模型

由于无约束区域的纤维增强聚合物 (FRP) 部分约束混凝土柱中的“拱形作用”的影响，与全包裹方案相比，用离散 FRP 条包裹的混凝土柱的约束效率较低。本研究综合研究了完全和部分FRP约束的圆形法强混凝土约束机制的差异，从而提出了一种新的面向设计的模型来预测部分FRP约束的法强混凝土的应力-应变关系。用于确定应力-应变曲线上几个关键点的强度和相应应变的公式也是根据相关文献中可靠的测试数据库通过回归分析提出的。除了，还收集了另一个选定的数据库，包括 100 个 FRP 部分包裹的圆形混凝土柱，用于模型验证。结果表明，与所选模型相比，新模型在预测部分 FRP 约束混凝土的极限条件方面具有更好的性能。最后，选择了一些样本来评估新模型在预测完整轴向应力-应变曲线方面的性能。比较表明，理论预测和实验观察之间可以达到令人满意的准确性和良好的一致性。结果表明，与所选模型相比，新模型在预测部分 FRP 约束混凝土的极限条件方面具有更好的性能。最后，选择了一些样本来评估新模型在预测完整轴向应力-应变曲线方面的性能。比较表明，理论预测和实验观察之间可以达到令人满意的准确性和良好的一致性。结果表明，与所选模型相比，新模型在预测部分 FRP 约束混凝土的极限条件方面具有更好的性能。最后，选择了一些样本来评估新模型在预测完整轴向应力-应变曲线方面的性能。比较表明，理论预测和实验观察之间可以达到令人满意的准确性和良好的一致性。