FRP复合加固钢筋混凝土梁的抗弯抗剪性能研究

发布时间：2018-10-19 13:29

【摘要】：外贴FRP加固技术(即EB-FRP:Externally-bonded fiber-reinforced polymer)由于FRP良好的力学性能广泛应用于结构加固领域,但由于FRP混凝土界面剥离破坏造成强度利用率过低,结构发生突然脆性破坏,整体延性性能较差,成为该加固方式发展的最大阻碍。目前很多学者提出很多方法来控制FRP的过早剥离,其中混合粘贴法(即HB-FRP:Hybrid-bonded fiber-reinforced polymer)结合机械锚固与外贴FRP法,对避免FRP剥离效果显著。本文对HB-FRP复合加固试验梁进行弯剪性能试验研究,并开发了一种新型延性机械装置,并采用端部锚固法(即EAB-FRP:End anchorage bonded fiber-reinforced polymer)进行抗弯加固,通过控制相应的试验变量来控制FRP剥离,提高FRP强度利用率,最终实现复合式机械加固混凝土结构的延性设计。本文还结合不同加固方式下的FRP界面极限粘结强度模型与试验梁极限弯剪承载力模型进行理论计算,考察所建立模型的合理性与有效性。抗弯试验中对加固梁底混凝土基体均采用机械凿毛的界面处理方式,适当布置改进的中部锚固装置与延性端部锚固装置,并对FRP加固钢筋混凝土梁进行受弯试验研究,分别通过控制中部紧固件的施加扭矩与延性端部锚固装置的变形段宽度来研究试验变量对试验梁极限抗弯承载力、延性性能、破坏形态与裂缝分布、FRP的应变分布与界面剪应力分布情况的影响。试验表明,两种加固方式均能显著提高加固梁的极限抗弯承载力与结构的延性变形性能,有效控制FRP剥离和提高FRP利用率,较大程度地提升了FRP界面粘结性能。抗剪试验中结合机械凿毛界面处理、“U形”粘贴FRP与中部锚固装置,对试验梁进行加固,并进行四点弯曲试验。通过控制中部锚固件的施加扭矩研究其对极限抗剪承载力、延性变形能力及FRP利用率的影响。试验表明,HB-FRP技术显著提高了加固梁的极限抗剪承载力与FRP利用率,一定程度上提高了延性变形能力,有效延缓和控制了FRP剥离破坏的产生。最后,结合不同加固方式下已经提出的FRP混凝土界面极限粘结强度模型与试验梁极限弯剪承载力模型,对比模型预测值与试验值发现,本文所选取模型预测精度较高,一定程度上为实际工程设计提供了较为可靠的设计依据。
[Abstract]:Due to the good mechanical properties of FRP, the externally bonded FRP strengthening technique (EB-FRP:Externally-bonded fiber-reinforced polymer) is widely used in the field of structural strengthening. However, the strength utilization ratio of FRP concrete interface is too low, the sudden brittle failure of the structure occurs, and the overall ductility of the structure is poor. It has become the biggest obstacle to the development of the reinforcement method. At present, many scholars have proposed many methods to control the premature peeling of FRP, in which the mixed bonding method (HB-FRP:Hybrid-bonded fiber-reinforced polymer) combined with mechanical anchoring and external sticking FRP method has a remarkable effect on avoiding FRP exfoliation. In this paper, the bending and shear behavior of HB-FRP composite strengthened test beam is studied, and a new ductile mechanical device is developed, and the end Anchorage method (EAB-FRP:End anchorage bonded fiber-reinforced polymer) is used for bending strengthening. The corresponding test variables are controlled to control the FRP peeling. The ductility design of composite mechanical reinforced concrete structure can be realized by improving the utilization ratio of FRP strength. The theoretical calculation of the ultimate bond strength model of FRP interface and the ultimate flexural shear capacity model of experimental beam under different reinforcement modes is also carried out in this paper. The rationality and validity of the established model are investigated. In the bending test, the reinforced concrete matrix under the beam is treated by mechanical hair-chiseling interface, the improved central anchoring device and the ductile end anchoring device are properly arranged, and the bending test of reinforced concrete beam strengthened by FRP is carried out. By controlling the applied torque of the middle fastener and the width of the deformation section of the ductile end Anchorage device, the ultimate flexural bearing capacity and ductility of the test beam are studied. The influence of fracture morphology, fracture distribution, strain distribution of FRP and shear stress distribution at interface. The test results show that the ultimate flexural capacity and ductile deformation of the strengthened beams can be significantly improved by both the two reinforcement methods, and the FRP peel and FRP utilization ratio can be effectively controlled, and the bond properties of FRP interface can be improved to a large extent. In shear test, combined with mechanical hair-chiseling interface treatment, "U-shaped" bonding FRP and the central Anchorage device were used to strengthen the test beam and carry out four-point bending test. The influence of the applied torque on ultimate shear capacity, ductile deformation capacity and FRP utilization rate was studied by controlling the applied torque of the central anchors. The test results show that HB-FRP technology can significantly improve the ultimate shear capacity and FRP utilization ratio of strengthened beams, improve the ductile deformation ability to some extent, and effectively delay and control the occurrence of FRP peeling failure. Finally, combining with the ultimate bond strength model of FRP concrete interface and the ultimate flexural shear capacity model of test beam, it is found that the model selected in this paper has high prediction accuracy. To some extent, it provides more reliable design basis for practical engineering design.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375.1

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