Experimental Study On Flexural Performance And Size Effect Of RC Beam Strengthened With Prestressed CFRP Plate

During with the rapid development of national economy and increasing transportation demand,substantial contribution was invested into traffic construction by government.But with the number of critically ill bridge increasing in the service process,the task of bridge maintenance and strengthening is getting heavy and complex.In this context,the safe and effective maintenance of the bridge is to restore the bearing capability and transportation capability of critically ill bridge and delay its service life,which makes it be able to continue to serve for modern transportation and modernization is of great significance and economic value.Strengthening technology with the prestressed CFRP plate(carbon fiber-reinforced polymer plate)can take full advantage of the high strength of CFRP plate performance,and improve its capability under force of the flexural member in the use of stage performance,which is a hotspot and focus of the bridge reinforcement research and application in recent years.The dimensions of the components used in the existing prestressed CFRP plate reinforcement test are small,and the research results can not guide the engineering practice well.Therefore,experimental study on flexural performance and size effect of RC beam strengthened with the prestressed CFRP plate has a great value for industrial application and scientific research.In this paper,six small-scale rectangular and three large-scale T RC beams were made.Prestressed reinforcement has being carried out for beams among them with Lika prestressed reinforcement system.This thesis studies the effect of prestressed CFRP plate reinforcement on the flexural behavior of RC beams and effect of size effect of specimen on reinforcement effect,and calculate the bearing capacity of the theoretical value.The main researches and conclusions are as follows:(1)Through the static load test of experimental beams,we have studied the features for debonding failure modes,bearing capacitylexural,rigidity and deformation ect;And the analysis of the strengthened with the bonded prestressed CFRP plate and the strengthened with the bonded unprestressed CFRP plate performance difference.The results are shown: By bonded prestressed CFRP plate can significantly improve flexural performance of the RC beams.And compared with non prestressed pasting CFRP plate reinforcement,prestressed pasting CFRP plate reinforcement can make and give full play to the performance of high strength of CFRP plate to use,slow component cracking,reduce the deformation,improve the bearing capacity and rigidity,etc.(2)By comparing the prestressed reinforcement effect of small-scale rectangular beams and large-scale T beams,size effect is studied on the influence of the prestressed reinforcement effect.The influence of the applied prestressed size on the reinforcement effect was studied by applying different prestressing tests to the test beams.Research shows that the size effect has an effect on the time of the CFRP plate stripped and whether whether it is completely peeled off.Stripping of large size components occurred after the steel yield,and after the two end points successively two stripping CFRP plate was not completely stripped,presents the obvious regularity.The greater the initial prestressing level applied to the specimen,the more obvious the effect of improving the bending resistance of the specimen,the greater the final utilization rate of CFRP plate.(3)For the specimen strengthened with the bonded prestressed CFRP plate,the adhesive layer between the CFRP plate and the concrete has played a very favorable role in the early rigidity of the specimen.The adhesive layer improves the integrity and the synergistic performance of the CFRP plate and the reinforced specimen(4)Through theoretical analysis,the judgment method of failure modes of RC beam strengthened with the bonded prestressed CFRP plate was given,and presente the theoretical analyses on the cracking load and ultimate load of RC beams strengthened with prestressed CFRP plate.