FRP增强预制裂缝混凝土的断裂性能

Fracture Characteristics of FRP Reinforced Precast Cracked Concrete

为了探讨纤维增强复合材料(FRP)增强预制裂缝混凝土的断裂性能,得到单层FRP对不同裂缝深度混凝土的最佳增强效果,通过相同尺寸、不同初始缝高比(0.2、0.3、0.4、0.5)的FRP增强预制裂缝混凝土三点弯曲梁断裂试验,基于FRP-混凝土界面黏结滑移模型,得到了FRP增强预制裂缝混凝土三点弯曲梁的断裂性能参数.结果表明:FRP增强预制裂缝混凝土的荷载-裂缝口张开位移(P-CMOD)曲线的峰值荷载大于普通混凝土的峰值荷载,且FRP增强预制裂缝混凝土峰值荷载随着初始缝高比的增加先增大后减小;初始缝高比从0.2变化到0.5时,FRP增强预制裂缝混凝土的起裂韧度可认为是常数;随着初始缝高比的增加,FRP增强预制裂缝混凝土的失稳韧度呈先增大后减小的趋势,当初始缝高比为0.4时,失稳韧度达到最大值,表明此时增强效果最佳;相比于普通混凝土失稳荷载后的脆性断裂破坏,FRP增强混凝土断裂破坏过程中的延性得到明显提高.

In order to study the fracture characteristics of fiber reinforced polymer(FRP) reinforced precast cracked concrete and obtain the best reinforcement effect of single layer FRP on concrete with different crack-depth ratio, the fracture tests of FRP reinforced precast cracked concrete three-point bending beams with the same size and different initial crack-depth ratios(0.2, 0.3, 0.4, 0.5) were carried out. Based on FRP-concrete interface bond slip model, the fracture parameters of FRP reinforced precast cracked concrete three-point bending beams were obtained. The conclusions can be drawn that, the peak load of FRP reinforced precast cracked concrete from the load-crack mouth opening displacement(P-CMOD) curve is much higher than that of ordinary concrete, and the peak load of FRP reinforced precast cracked concrete increases first and then decreases with the increase of crack-depth ratio. In the range of crack-depth ratio from 0.2 to 0.5, the initial crack toughness of FRP reinforced precast cracked concrete can be considered as a constant. The instability toughness of FRP reinforced precast cracked concrete increases first and then decreases with the increase of crack-depth ratio. When the crack-depth ratio is 0.4, the instability toughness reaches the maximum, which indicates that the reinforcement effect is the best. Compared with the brittle fracture failure of ordinary concrete under instability load, the ductility of FRP reinforced precast cracked concrete during fracture failure process is significantly improved.