HB-FRP加固混凝土梁研究综述

为总结混合粘贴纤维复合材料(HB-FRP)加固方法的研究成果, 推动其在混凝土梁维修加固领域的更广泛应用, 调研了HB-FRP加固法的研究现状, 揭示了外贴HB-FRP在外荷载和环境侵蚀下容易发生剥离的问题; 阐述了HB-FRP抑制FRP加固后剥离的工作机理, 分析了HB-FRP加固体系的构造特征及其对界面黏结力的影响; 总结了已有黏结-滑移模型和剥离荷载模型, 研究了加固梁的抗弯和抗剪性能; 分析了当前工作的不足, 并展望了下一步的研究方向和思路。分析结果表明: 外荷载和环境侵蚀均可能引起FRP剥离, HB-FRP加固同时发挥了化学黏结、摩擦和销栓作用, 有效地抑制了FRP剥离; 目前几种HB-FRP黏结-滑移关系的主要区别为达到界面黏结强度时FRP是否会发生稳定的滑移; 黏结界面极限剥离荷载取决于其黏结-滑移关系; HB-FRP加固可用于正截面抗弯和斜截面抗剪, 加固梁承载力和加固效率可得到大幅提高; 增加FRP配置率和钢扣件数量能有效提高加固梁的抗弯能力, 钢扣件间距对加固梁承载力的影响和加固设计准则还不明确, 裂缝和外荷载对加固梁的剥离荷载、材料利用率和破坏模式影响显著; 加固梁抗剪强度的增加主要来自FRP和混凝土提供的剪力, 而箍筋的影响较弱; 增加FRP加固量和减小条带间距能显著提高加固梁的抗剪承载力; 后续应继续研究HB-FRP加固设计理论, 提出考虑材料与构造特征的黏结特性计算模型和基于界面剪力的HB-FRP钢扣件间距设计方法, 进而建立HB-FRP加固混凝土梁的优化抗弯、抗剪设计方法和设计公式。 

Review on research on concrete beam reinforced with HB-FRP

To summarize the research results of hybrid bonding fibre reinforced plastic(HB-FRP) reinforcement method and promote its broader application in the field of concrete beam repair and reinforcement, the research status of HB-FRP reinforcement method was investigated. The debonding problem of external bonding FRP under external loads and environmental erosion was revealed. The working mechanism of HB-FRP reinforcement in inhibiting debonding after FRP reinforcement was explained. The structural characteristics of HB-FRP reinforcement system and its influence on the interface bonding performance were analyzed. Existing bonding-slip and debonding load models were summarized. The flexural and shear performance of reinforced beam was studied. The shortcomings of existing studies were analyzed, and future research directions and ideas were prospected. Analysis result shows that both external loads and environmental erosion may induce the debonding of FRP. HB-FRP reinforcement combines the chemical bonding, friction and dowel effect to inhibit the FRP debonding effectively. The main difference among several current HB-FRP bond-slip relationships is whether a stable FRP slip occurs when the interfacial bonding strength is reached. The limit debonding load of the bonding interface depends on its bond-slip relationship. HB-FRP reinforcement can be used for the flexural resistance of normal section and the shear resistance of oblique section, and the bearing capacity and reinforcement efficiency of reinforced beam improve significantly. Increasing the FRP amount and the number of steel fasteners can effectively improve the flexural resistance of reinforced beam. The influence of steel fastener spacing on the bearing capacity of reinforced beam and the reinforcement design criteria are still unclear. The crack and external load have significant effects on the debonding load, material utilization rate, and failure mode of reinforced beam. The increase in the shear strength of reinforced beam mainly generated by the shear forces provided by the FRP and concrete, whereas the influence of stirrup is minimal. The increase in the FRP reinforcement amount and the decrease in the strip spacing can significantly improve the shear capacity of reinforced beam. Follow-up studies on the HB-FRP reinforcement design theory should be continued to propose calculation models for bonding characteristics considering the material and structural characteristics and develop a design method for HB-FRP steel fastener spacing based on the interfacial shear force. Furthermore, the optimized flexure and shear resistance design methods and design formulas for HB-FRP reinforced concrete beams should be developed.