Prestressed Carbon Fiber Reinforced Concrete Beams Shear Properties Of The Test Study

As a new structural engineering material, continuous carbon fiber sheet (CFS) has many advantages, such as excellent mechanical and deforming properties convenience in use, almost weightless comparing RC members , no extra space occupation, and immunity to corrosion. If reinforced concrete members are strengthened by non-prestressed carbon fiber sheet, before making full use of the strength of carbon fiber sheet the width of cracks has been beyond the upper limit specified in governing code. This paper introduces the existing reinforcement technologies and the application and the future development of carbon fiber reinforced plastics, also discusses the advantages and defects of such reinforcement technology. Finally the paper brings forward that strengthening concrete members by prestressed carbon fiber sheet is an effective method decreasing the width of cracks.The research based on experiments of six reinforced concrete beams strengthened against shear damage. During the research we developed special devices to stress U style stirrup of carbon fiber sheet, and compared deflection, cracks, ultimate load of RC beams in which some was strengthened by prestressed U style stirrup of carbon fiber sheet and the other was strengthened by non-prestressed U style stirrup. I generally analyzed the effectiveness of the prestressed strengthening method on the working performance of RC beams.Experimental results prove that the method of strengthening RC beams by prestessed U style stirrup of carbon fiber sheet is effective in decreasing and controlling cracks . It can also improve destruction mode of the structure. Shear capacity of the strengthened RC beams is improved notably. The upper limit of shear capacity can be calculated by the formula in governing code "strengthening concrete structure technology instruction on carbon fiber sheet" CECS 146:2003.Finally, this paper put forward a new technics on prestressing carbon fiber sheet. The technics fit for strengthening RC members against shear damage. Its effectiveness was successfully proved in the experiment.