Experimental Study On Large-tonnage Prestressed Carbon Fiber Reinforced T Beam

Compared with steel strands used in conventional external prestressed reinforcement methods,carbon fiber sheets have strong corrosion resistance,high strength,low self-weight,easy formation of pre-stressed bonded reinforcement,and excellent fatigue performance and long-term performance.However,in the actual bridge reinforcement project,due to the clamping performance of the carbon fiber board fixture,the tensile force of the single carbon fiber board is not large.The tension of a single piece of carbon fiber sheet is usually only 120 kN,while the tensile tonnage of a c015.2 strand is 194 kN.Obviously,the monolithic prestressed carbon fiber board can hardly meet actual needs in the reinforcement project.Therefore,it is very necessary to study the method of strengthening the large tonnage of multiple sheets of carbon fiber sheets at one time.Therefore,in this paper,the prestressed CFRP-reinforced concrete T-beams were studied using a reliable carbon fiber sheet wave anchorage and hinged anchor tensioning technology.In this paper,two sets of single-deck and double-deck pre-stressed carbon fiber reinforced concrete T-beam reinforced concrete T-beams were set up,and the initial prestresses of 1200Mpa and 900Mpa were applied to the single and double-strengthened carbon fiberboards.The main results are as follows:(1)In the tension stage of double-prestressed carbon fiber sheet,the strain of the outer carbon plate is basically the same,and the inner and outer carbon plates are coordinated by force.The amplitude of single-and double-layer prestressed carbon fiber sheets is consistent with that of tensioned steel bars in the use of load stage,and the overall stress coordination of single and double prestressed carbon fiber reinforcements.(2)The flexural deformation of the flexural member reinforced with prestressed carbon fiber sheet is inversely proportional to the applied prestress.The greater the prestress applied,the smaller the flexural deformation of the reinforced flexural member.(3)The reinforcement of double-layer prestressed carbon fiber sheet can inhibit the crack development of beam better than the reinforcement of single-layer prestressed carbon fiber sheet.The crack width of the bending member is inversely related to the prestressed tensile tonnage of the reinforced carbon fiber sheet.(4)The cross-section strain distribution of reinforced concrete beams strengthened by single and double prestressed carbon fiber plates meets the flat section assumption.(5)Single-layer and double-layer prestressed carbon fiber sheets have less prestress loss during the tension stage,and the main prestress loss occurs during the use load stage and is caused by the concrete's later shrinkage and creep.The relaxation loss caused by laying prestressed carbon fiber composite plates in the prestressing stage is the main reason for the difference in prestress losses between single-layer and double-layer prestressed carbon fiber plates.(6)In this paper,the calculated value of the reinforced concrete beam with prestressed carbon fiber board is smaller than the experimental value.The ultimate load calculated from the ultimate strength of the tensile reinforcement is more accurate than that calculated from the yield strength of the steel.(7)The deformation results calculated by the deflection calculation theory used in this paper agree well with the test values,which shows that it is reliable to use direct bilinear method to calculate the deformation of the prestressed carbon fiber sheet reinforced bending members.