预应力纤维布加固混凝土圆形截面短柱轴压性能试验

为研究环向预应力纤维布加固混凝土圆形截面短柱的轴心受压性能，制作25个试件并进行轴心受压试验。试验考虑的影响因素包括：试件的混凝土强度等级、截面尺寸、箍筋间距、既有损伤及表面处理情况、纤维布种类、层数和预应力大小。试验得到了各个试件的破坏形态和应力 应变关系，进而分析了各影响因素对加固效果的影响。结果表明：与非加固试件相比，环向预应力纤维布加固试件的轴心受压承载力和延性均有明显提高；对纤维布施加预应力能避免纤维布的应力滞后，更好地发挥纤维布的高强性能；当环向预应力与纤维布的抗拉强度的比值在0～0.20范围内，试件的承载力和延性随预应力的增大而增大；当环向预应力达到纤维布抗拉强度的0.25倍时加固效果会降低，因此在工程应用中环向纤维布的预应力宜控制在纤维布抗拉强度的0～0.20倍之间。

Experimental study on circular concrete short columns strengthened with pre-stressed FRP under axial compression

To study the axial compressive performance of circular concrete short columns strengthened with lateral pre-stressed fiber reinforced polymer (FRP), 25 specimens were manufactured and tested under axial compression. The main factors considered in the experiment included concrete strength, cross section size, spacing of stirrup, initial damage and surface treatment of the specimens, pre-stressing level, type and layers of FRP. The failure mode and the stress-strain curve of each specimen were obtained from the experiment and the impact on confining effect of various factors was analyzed. Experimental results show that the strength and ductility of circular concrete columns strengthened with lateral pre-stressed FRP can be improved significantly relative to the un-strengthened specimen, the stress hysteresis of lateral FRP can be avoided by pre-stressing, and the high strength of FRP can be better used. When the pre-stressing of lateral FRP within 0～0.20 times of its ultimate tensile strength, the strength and ductility of specimens increase with the increase of lateral FRP’s pre-stressing. The strengthening effect will be reduced when the pre-stressing of lateral FRP reacheds 0.25 times of its ultimate tensile strength. So the pre-stressing of lateral FRP should be controlled within 0～0.20 times of its ultimate tensile strength in practice.