纤维复材网格增强水泥基复合材料加固锈蚀钢筋混凝土梁受力性能研究

Aiming at the problems of quickly repairing and strengthening for corroded RC beam, a new strengthened technique is developed by using FRP grid reinforced engineering cementitious composite (ECC) as composite strengthened layer to improve the mechanical behavior and durability of corroded RC beam, to overcome disadvantages of externally bonded FRP technique such as poor durability and resistances of fire. The research plan focus on mechanical behavior of corroded RC beams strengthened with FRP grid reinforced engineered cementitious composites. A series of tests are conducted to determine the optimum proportion of wet spraying ECC. The effect of strength of concrete, interface treatment methods and interface finishing agent on mechanical properties of the bond between wet spraying ECC and concrete is investigated and a prediction model is then proposed to for the strength of the bonding interface. FRP grid reinforced wet spraying ECC is conducted under uniaxial tensile loading. Based on the experimental results and theoretical analysis, a stress-strain model of FRP grid reinforced ECC is established. Corroded RC beams strengthened with FRP grid reinforced ECC are tested under flexural, shear and fatigue loading to investigate their bending, shear, creep and fatigue properties. Theoretical analysis and tested study are combined to propose a design method of corroded RC beams strengthened with FRP grid reinforced ECC under flexural and shear loading. The equations are also formulated for calculating the creep and fatigue life.

针对氯离子腐蚀环境下锈蚀钢筋混凝土（RC）梁的快速修复加固问题，将锈蚀胀裂的混凝土保护层置换为高延性的纤维水泥基复合材料（ECC），纤维复材（FRP）网格配置于ECC内，形成FRP网格增强ECC加固锈蚀RC梁技术，克服外贴FRP片材加固技术中界面粘结剂耐久性差、耐火性不足等缺点，实现快速修复、受力性能和耐久性能提升的多重效果。项目首先开展湿喷ECC的制备研究；然后进行湿喷ECC与既有混凝土粘结性能研究，分析不同既有混凝土强度、界面处理方式等对界面粘结性能的影响规律，建立界面粘结强度模型；开展FRP网格增强ECC抗拉性能研究，建立相应的抗拉本构关系模型；在此基础上，开展FRP网格增强ECC加固锈蚀RC梁的受弯、受剪、徐变和疲劳性能研究，分析各种受力条件下加固锈蚀RC梁的工作机理，提出加固锈蚀RC梁承载力设计方法，建立加固锈蚀RC梁的徐变计算模型和疲劳寿命预测模型。

针对锈蚀钢筋混凝土梁的快速修复加固问题，将锈蚀胀裂的混凝土层置换为高延性的纤维水泥基复合材料（ECC），复材（FRP）网格配置于ECC内，形成FRP网格增强ECC加固锈蚀钢筋混凝土梁技术，克服外贴FRP片材加固技术中界面粘结剂耐久性差、耐火性不足等缺点。项目开展湿喷ECC的配合比设计研究，采用国产PVA纤维制备出极限拉应变达3.49%的ECC，给出了配合比；研究ECC与既有混凝土粘结性能以及FRP网格增强ECC抗拉性能，结果表明粘结强度随粘结面粗糙度增大而提高，且在粘结面湿饱和状态时浇筑更加有利于界面粘结强度的提高；与普通ECC试件相比，FRP网格增强ECC的轴向刚度、极限拉应变和抗拉强度均得到较大程度提高，二者协同工作性能良好；建立了ECC与既有混凝土粘结强度模型和FRP网格增强ECC的应力-应变本构方程。在此基础上，开展FRP网格增强ECC加固锈蚀钢筋混凝土梁的受弯、受剪、徐变和疲劳性能研究，分析锈蚀率、FRP网格类型和加固量等因素对加固锈蚀钢筋混凝土梁破坏模式、承载力、刚度等特性的影响。结果表明：采用FRP网格增强ECC置换锈蚀损伤混凝土层能有效提升梁的刚度和承载能力，与未加固锈蚀钢筋混凝土梁相比，加固梁的受弯和受剪承载力分别最高提升62.09%和36.44%，FRP网格利用率最高可达85.31%；提出了加固锈蚀钢筋混凝土梁受弯和受剪承载力计算公式；该修复加固体系对锈蚀钢筋混凝土梁的徐变挠度有明显抑制作用，且随着FRP网格加固量的增加，挠度抑制作用逐渐增强；与未加固的锈蚀钢筋混凝土梁相比，加固梁的疲劳寿命得到了显著提升，且提升幅度随着FRP网格加固量的增大而提高；建立了加固锈蚀钢筋混凝土梁的徐变计算模型和疲劳寿命预测模型。项目为锈蚀钢筋混凝土梁修复加固提供了一种新的方法，可实现快速修复、受力性能和耐久性能提升的多重效果，计算理论可为工程应用提供参考。

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