Research On The Mechanical Property Of The Ancient Brick Pagodas Strengthened By Prestressed CFRP Plate Hoops

To our country, it is an important work for the protection of ancient buildings in the coming period to carry out seismic rehabilitation and seismic reinforcement for remaining ancient pagodas. And the introduction of carbon fiber board in the reinforcement of ancient pagoda is regarded as the combination of the protection of typical ancient pagoda and the popularization and application of new materials.Compared with steel and carbon fiber cloth, carbon fiber board has potential application prospect in the project of repairing and strengthening the ancient brick pagoda. This article puts forward the technique of using prestressed carbon fiber board to hoop and reinforcement which aims at the destructive characteristic of vertical layout of masonry pagodas and the requirement of enhancing the structural integrity, and completed the experimental study on the ancient pagoda hexagonal scale model with self-developed tension and anchor device. Successively investigate the working performance of the tension anchor device and carbon fiber board, analyze the law of the distribution of prestress along carbon fiber board and masonry, and discuss the change rule of working stress along with time as carbon fiber board keep tensioned. Furthermore, a new technique of using curvilinear tensioned carbon fiber plate is raised to overcome the phenomenon of inhomogeneity of stress. Model test and finite element modeling method are also used to prove the rationality and necessity of adding curvilinear plate. Specific work includes the following content:(1) Complete two patents:combine with the model test of prestressed carbon fiber board hoops and the actual engineering requirements, the integrated device to tension and anchor prestressed carbon fiber board is developed. This device can effectively anchor the carbon fiber board and complete tension efficiently, simultaneously can form the prestressed hoop system on ancient pagoda; Proposed the method of reinforced concrete beam strengthened with curvilinear tensioned carbon fiber plate, and this improved scheme was used on model test. This paper comprehensively introduces the design scheme of curvilinear concrete plate, and implementation method to reinforce masonry.(2) Carried out short-term tension test study:include reinforced test by prestressed carbon fiber board hoops with the method of tension at one end, and reinforced test with the methods of tension at boths ends and adding curvilinear plate. And successfully applied the designed tension and anchor integration device to the test model. Then respectively completed hoop tension test under 10%、30%、50% prestressing degree and over tensioning test, as to investigate the working performance of the tension anchor device and carbon fiber board, verify the function of over tensioning, and analyze the law of the distribution of prestress along carbon fiber board and masonry. At the same time, the advantages and disadvantages of the two methods are compared and analyzed,the effort of improving stress inequality with the method of tension at both ends and adding curvilinear plate wrer verified, and different rise-span ratio of curvilinear plate which is better to relieve local stress was determined.(3) After the completion of the 50% prestressing degree applied, maintenance the prestressing degree to carry out long-term loading test, collect the strain changes in carbon fiber plate and masonry for one month of three groups respectively, and discuss the change rule of working stress with time as carbon fiber board is tensioned.(4) Simulate and verify the reliability and accuracy of the model test by ANSYS, and realize the guidance of the actual reinforcement. In addition, explore the method of dividing masonry and carbon fiber board and how to set the friction element between the brick and the carbon fiber plate, which can provide some reference for the similar hoop reinforcement.Through induction and comparison of three groups of short-term tension and long-term tension experiments, this paper systematic studied the distribution law of strain along the carbon fiber sheet and masonry and the change law of strain with time, which can provide theoretical and practical reference for the similar reinforcement study of carbon fiber board. Moreover, no matter used to reinforce masonry structure ancient architecture or modern concrete beam bridge and other bending members, the integrated device to tension and anchor and the construction technology and reinforcement method of curvilinear concrete plate both have strong abilities to apply. Therefore, it will have broad application prospects in the field of reinforcement engineering.