Pre-tension control of reinforced concrete beam strengthened with CFRP sheets

A calculation model for the interfacial shear stress of the reinforced concrete beam strengthened with prestressed CFRP sheets was built based on the elasticity theory after releasing and loading. The changes of the interfacial shear stress under the preload and the external load and the distribution of the effective tension stress in the CFRP sheers were calculated. The calculation results coincided with the results of test and the results of the finite element analysis. It was concluded that the optimization of the strengthening by the pritension control of the reinforced concrete beam strengthened with the CFRP sheets can only be realized under the condition of overall consideration on three major factors, i.e. the buckling stress on the top of the concrete beam after releasing, the interfacial shear stress and its increment after external loading.