Study On Concrete Beams Strengthened In Flexure With End-anchored Prestressed Steel Plate

steel bonded technique is widely used in civil engineering, because the steel plate has many characteristics, such as high strength, good ductility, good weld ability and convenience construction. However, the adhesive can be debonding when steel plate bonded to structures for strengthening, which cannot make full use of the high strength of steel plate and prevent the propogation of existing cracks. If the steel plate was prestressed and end-anchored before they bond to deteriorated structures, these problems can be solved effectively. Based on background of a box girder bridge which in need of rehabilitation for floor cracks, this research focuses on the flexural behavior of the RC beams strengthened by a new designed anchorage system used for prestressed steel in the end of concrete beam. The main work and conclusion as follows:1、 theoretical analysisAccording to the characteristics of end anchorage, this paper make some assumptions of the concrete beams strengthened with end-anchored prestressed steel plate. Based on the assumptions, the formulae of cracking load, yield load, ultimate load of the are deduced to predict the test result.2、Experiment investigationThis research uses a new designed end anchor system of prestressed steel plate in RC flat beams strengthened with steel plate.Five rectangular beams were tested which considering prestress and reinforcement ratio as parameter. During the experiment, the development of cracks and deformations were observed.Analyzed the damage form of the beam, the curve of steel strain in the mid-span section, rod strain curves, the load-deflection curves of the beam.Discussed the effect of the prestressed and reinforcement ratio on crack width and the characteristic loads.3、design applicationBased on the theory and test results, aflexural capacity formula for the RC beams strengthened with end-anchored prestressed steel plate is proposed. Some advices for the builders in strengthening construction are given then.