It is widely accepted that concrete columns confined with fiber-reinforced polymer (FRP) jackets exhibit significant increases in strength and ductility with reference to the unconfined case. Existing experimental studies have indicated that the hoop rupture strains measured in the FRP jackets are significantly lower than the material strain capacity determined by the flat coupon tensile tests. An FRP efficiency factor is then usually used to define the ratio of the average hoop rupture strain to the material strain capacity of the FRP jackets, which governs the lateral FRP confinement as well as the peak strength and ultimate strain of the FRP-confined concrete under axial compression. FRP jackets are also expected to be a promising solution to repair damaged RC columns after fire exposure. However, there is lacking research on the behavior of FRP-confined fire or heat-damaged concrete columns. In particular, the FRP efficiency factor of FRP-confined fire or heat-damaged concrete columns has not yet been established. The study presents the results of an experimental study aimed to investigate the effects of the historical high temperature and the layer of basalt FRP (BFRP) jackets on the efficiency factor of BFRP for the confined heat-damaged concrete cylinders. A sum of 51 standard concrete cylinders is prepared and tested under axial compression. The parameters varied between tests are the historical high temperature (200°C, 400°C, 600°C, or 800°C) that is used to produce the heat damage of concrete cylinders and the number of layers of BFRP jackets (2, 3, or 4). The test results have indicated that the efficiency factor of BFRP jackets increases with the historical high temperature but decreases slightly with the increase in the BFRP layers. A new temperature-dependent design equation for the BFRP efficiency factor of the confined heat-damaged concrete is proposed to consider the effects of the parameters mentioned above and can be used for practical design.

人们普遍认为，与无约束情况相比，用纤维增强聚合物 (FRP) 护套约束的混凝土柱在强度和延展性方面表现出显着增加。现有的实验研究表明，在 FRP 护套中测量的环向断裂应变明显低于由扁平试样拉伸试验确定的材料应变能力。然后通常使用 FRP 效率因子来定义平均环向断裂应变与 FRP 护套的材料应变能力之比，该比决定 FRP 约束的横向约束以及 FRP 约束混凝土的峰值强度和极限应变。轴向压缩。FRP 护套也有望成为在火灾暴露后修复受损 RC 柱的有前途的解决方案。然而，缺乏对 FRP 围火或热损坏混凝土柱行为的研究。特别是，FRP 围火或热损坏混凝土柱的 FRP 效率系数尚未确定。该研究展示了一项实验研究的结果，旨在研究历史高温和玄武岩 FRP (BFRP) 夹套层对受限热损坏混凝土圆柱体的 BFRP 效率系数的影响。准备了 51 个标准混凝土圆柱体，并在轴向压缩下进行了测试。测试之间不同的参数是用于产生混凝土圆柱体热损伤的历史高温（200°C、400°C、600°C 或 800°C）和 BFRP 夹套的层数（2， 3 或 4）。试验结果表明，BFRP 夹套的效率系数随着历史高温而增加，但随着 BFRP 层数的增加而略有下降。考虑到上述参数的影响，提出了约束热损伤混凝土的BFRP效率因子的新的温度相关设计方程，可用于实际设计。