Study On The CFRP Reinforced Concrete Beam With Corroded Stirrups

Reinforcement corrosion is one of the main causes of the destruction of concrete structures.The corrosion of stirrups has a great influence on the shear failure of reinforced concrete beams.At this stage,it is necessary to study the mechanical properties and reinforcement methods of corroded reinforced concrete structures and the method of CFRP is an efficient structural reinforcement method.When the stirrups are corroded,the carbon fiber sheet is attached to the bottom of the beam,which not only can improve the ultimate bearing capacity but also change the failure mode of the concrete simply supported beam.First of all,the flexural failure test of reinforced concrete simply supported beam and the failure test of simply supported CFRP beams under CFRP are carried out in this paper.Based on the analysis of the test results,it is concluded that CFRP can greatly increase the ultimate bearing capacity of concrete simply supported beams.The model of reinforced concrete simply supported beam is established by using finite element software.Then the test results are compared with the established finite element model to verify the rationality of the model.Secondly,when the stirrups are corroded,the reinforced concrete beams of which are pasted with carbon fiber cloth at the bottom are studied.In the case of different corrosion rates,the ultimate bearing capacity and the failure morphology of the concrete simply supported beam change with the different number of layers of CFRP.The results show that the flexural performance of concrete simply supported beam increases with the increase of the number of CFRP sheets at the bottom of the concrete simply supported beam;With the increase of the number of layers of CFRP,the concrete simply supported beams change from flexural failure to shear failure.Finally,the effect of U-shaped CFRP reinforcement on the shear span of beams is studied for concrete simply supported beams with the corrosion of stirrups.With the change of the corrosion rate of the stirrups,the concrete simply supported beams which may be damaged of the shear failure are strengthened in the shear span with CFRP and the carbon beam is strengthened.The stress-load curve of the stirrup and longitudinal reinforcement of the concrete simply supported beam is analyzed.The results show that the stress of the stirrups is seriously reduced with the increase of the number of layers of the CFRP in the shear span.When the concrete simply supported beam reaches the ultimate bearing capacity,the stirrup does not yield and the longitudinal reinforcement suits,at the same time,the concrete simply supported beams are damaged with the bending failure.The optimal number of layers of CFRP corresponding to different corrosion rates was found by analysis.