【摘要】 HB-FRP加固带初始裂缝桥梁正常使用阶段的受力性能需开展评估。基于单元法和直接法生成带初始裂缝的多梁式T梁有限元模型,单元法用于评估FRP界面黏接性能,直接法引入弹性断裂力学基本理论,基于虚拟裂纹闭合法计算初始裂缝的裂尖能量释放率,探讨HB-FRP加固前后的裂缝扩展风险。研究结果表明:车辆荷载作用下,如果梁体无初始裂缝,FRP应力和FRP-混凝土的黏接应力均很小,安全富余度较高;多梁式T梁偏载部位梁体跨中弯曲裂缝处FRP-混凝土黏接应力最大,HB-FRP加固时,轮载作用下极易出现中部弯曲裂缝导致的界面剥离(IC剥离),小于4倍设计轮载情况下,HB-FRP加固裂缝位置发生界面剥离,但钢扣件的抑制剥离效果使IC剥离范围大幅度减小;裂缝越高,裂缝尖端的G_Ⅰ值越大,裂缝越不稳定,越容易扩展;正常使用阶段初始裂缝位置越高,HB-FRP加固抑制裂缝扩展的加固效果越弱,因此发生弯曲裂缝病害的桥梁应尽早加固。更多还原

【Abstract】 The multi T-beam finite element model with initial cracks is generated based on the element method and the direct method. The element method is used to evaluate the bonding performance of the FRP-to concrete interface. The direct method introduces the basic theory of elastic fracture mechanics and calculates the crack tip energy release rate of the initial crack based on the virtual crack closure method, the crack propagation risk before and after HB-FRP reinforcement is discussed. The research results show that: under traffic load, if there is no initial crack, the FRP stress and the bonding stress of FRP-concrete are very small, which indicates the structure is safe. The FRP-concrete bonding stress is the largest at the flexural crack of the beam mid-span of the multi T-beam’s eccentric load position. When using EB-FRP reinforcement, the interface debonding caused by the middle flexural crack is easily under traffic load. In the case of overloading less than 4 times the design traffic load, the interface debonding occurs at the crack of the beam reinforced by HB-FRP, but the debonding suppression function of the mechanical fastener has greatly reduced the IC debonding. The higher the crack, the greater the G_I value at the crack tip, the more unstable the crack, and the easier it is to propagate. The higher the initial crack position, the weaker the effect of HB-FRP reinforcement to suppress crack propagation. Therefore, bridges with flexural cracks should be strengthened as soon as possible.更多还原