Research And Application Of Pre-stressed Carbon Fiber Sheet In Bridge Strengthening

In recent years,with the continuous development and improvement of existing bridge reinforcement and maintenance technology in China,pre-stressed carbon fiber sheet reinforcement technology has become a hot spot and frontier in the field of bridge reinforcement due to its superior mechanical properties,simple construction technology and good economic benefits.The most critical problem in the pre-stressed carbon fiber sheet reinforcement technology is the anchorage of CFRP.Although many scholars at home and abroad have done a lot of research and experiments on the pre-stressed carbon fiber sheet reinforcement technology,it is still not well solved,so the pre-stressed carbon fiber sheet reinforcement technology can not be widely used.Therefore,it is of great value and significance to develop a reliable anchorage for the reinforcement technology of pre-stressed carbon fiber sheet and to analyze the actual reinforcement effect.The following is the research content and results of this paper.(1)Aiming at the anchorage problem of pre-stressed carbon fiber sheet,a wedge-shaped pressure carbon fiber sheet anchorage is developed.Through static load anchorage performance tests of several groups of anchorage assemblies with different manufacturing parameters,the manufacturing parameters of the anchorage were determined,and then the fatigue performance of the anchorage was tested,and a series of anchorage products with different specifications and models were formed.According to the results of static load anchorage test and fatigue performance test,the efficiency coefficient of the anchorage is stable at more than 90%,which meets the requirements of efficiency coefficient and fatigue performance of the anchorage in the relevant national standards.The anchorage has been patented as a practical new type.(2)Based on the flexural strengthening engineering practice of a T-beam bridge,the tension loss and relaxation loss of the pre-stressed carbon fiber sheet are detected by using fiber Bragg grating technology.According to the test results,the loss of pre-stress tension is 8.02%~9.01%,and the loss of stress relaxation is 1.42%~1.98% in three months.The formulas for calculating the flexural capacity of T-beams are given through theoretical analysis,and the maximum deflection of the span before and after reinforcement is compared by using MIDAS Civil finite element software.The results show that the maximum deflection of T-beams in the span decreases in varying degrees under various working conditions,which shows the effect of pre-stressed carbon fiber sheet in the actual bridge flexural strengthening.(3)Combining with the practice of transverse reinforcement of a hollow slab girder bridge with pre-stressed carbon fiber sheet,the maximum deflection of the span before and after reinforcement is compared by using MIDAS Civil finite element software.The results show that the deflection and displacement of each hollow slab beam are more uniform after reinforcement,which improves the lateral distribution of load and the overall bearing capacity of the bridge.