FRP包裹混凝土圆柱统一约束模型

为进一步明确纤维增强复合材料(FRP)约束混凝土圆柱轴压性能影响因素及现有约束模型适用性,收集了混凝土强度在6.2～188.2 MPa范围内的普通混凝土、高强混凝土、超高性能混凝土、再生混凝土、海水海砂混凝土和工程水泥基复合材料等1049组普通FRP/大应变FRP包裹圆柱的试验数据.在统计分析基础上,基于最小二乘法建立...

A Unified Confinement Model of FRP-Wrapped Concrete Cylinder

The purpose of this study was to achieve a comprehensive understanding of the compressive behavior of FRP-confined concrete cylinders and the applicability of existing confinement models. A total of 1 049 groups of experimental results of conventional fiber-reinforced polymer (FRP) or large rupture strain (LRS) FRP-wrapped normal concrete, high-strength concrete, ultrahigh-performance concrete, recycled aggregate concrete, seawater sea-sand concrete, and engineered cementitious composite with unconfined concrete strength in the range of 6.2-188.2 MPa were assembled. Based on data analysis, a prediction equation for the FRP hoop rupture strain reduction coefficient with higher accuracy was formulated using the least-squares method. The effects of the FRP type and the concrete strength and type on the peak strength and ultimate strain were studied. The results show that at a given actual confinement ratio, the FRP type has a negligible effect on the peak strength but has a significant effect on the ultimate strain. LRS FRP can significantly improve the ductility of confined cylinders, which is more suitable for the seismic reinforcement of bridge piers. The increase in concrete strength reduces the confinement effectiveness of the FRP, resulting in a relatively small enhancement ratio of the peak strength and ultimate strain. Compared with other types of concrete with the same compresive strength, the confined high ductile engineered cementitious composite has a lower strength enhancement. Finally, the prediction effect on the peak strength and ultimate strain of the existing confinement models was evaluated using the average absolute error (A_AE), mean (M), and standard deviation (S_D). A unified confinement model considering the FRP type and the concrete strength and type is proposed. The A_AE values of peak strength and ultimate strain predictions obtained by the proposed model are 0.13 and 0.31, respectively. This model can serve as a simplified formula to estimate the peak strength and ultimate strain of various types of concrete confined with FRP.