Analysis Of Bending Reinforcement Of Pretensioned PC Hollow Slab Beam Based On Full Scale Test

The vast majority of existing bridges in China are ordinary reinforced concrete girder bridges and prestressed concrete girder bridges.With the increase of service time and the increase of load levels,many bridges can no longer meet the requirements for strength,stiffness,stability and durability.Therefore,maintenance,reinforcement and reconstruction are required.In this paper,after consulting a large number of domestic and foreign data on the anti-buckling reinforcement of prestressed concrete beams,the development history and research status of the reinforcement of prestressed concrete bridges are summarized,and several commonly used methods for bridge reinforcement are introduced.The test relied on 16m prestressed reinforced concrete hollow slab beams that had been in service for 20 years and was abandoned in the reconstruction and expansion project of three highways.Based on the durability testing of the test beams and the inspection of the mechanical properties of the materials,the reinforcement scheme was determined.The test beam is arranged with reasonable measuring points.In the process of applying the load,the strain and deflection of the test beam were collected in the whole process,and the test results were analyzed.Considering the stress of the two stages after the reinforcement of the test beam,under different initial strain conditions,the expression formulas of the relative limit height coefficients under three different conditions are deduced.A formula is proposed for the relationship between the height of reinforced concrete and resistance to external loads.When the height of newly added concrete reaches a certain value,the reinforced beam resists the maximum value of external load bending moment.Based on this,the relationship formula between the new concrete and the carbon fiber board under the joint action of resisting external loads was deduced.Analyze the ultimate bearing capacity of the finite element model using different reinforcement methods.It is found that both the reinforced section method with reinforced zone and the CFRP plate reinforcement method can effectively increase the cracking load and ultimate bearing capacity of the test beam.Increasing the cross-section reinforcement method is more important for strengthening the test beam than the carbon fiber reinforcement method.