A parametric study on the effectiveness of the NSM technique for the flexural strengthening of continuous RC slabs

Abstract

Recent experimental research has shown that the Near Surface Mounted (NSM) technique has significant potential for increasing the load-carrying capacity of continuous reinforced concrete (RC) slabs. This flexural strengthening technique is based on the installation of rectangular cross sectional carbon fibre reinforced polymer (CFRP) laminates into thin slits that have been opened into the top concrete cover on intermediate supports as well as into the bottom concrete cover in the tensile zones.However, there are several drawbacks to the NSM technique. The linear-elastic behaviour of the CFRP laminates, combined with the possibility of premature detachment of the concrete cover that includes these laminates, can compromise the effectiveness of the flexural strengthening, the moment redistribution and the ductility performance of this type of structure.In order to evaluate the influence of concrete strength, the strengthening configuration, the percentage of CFRP on the load-carrying capacity, the moment redistribution ability and ductility performance of this type of structure, a parametric study was carried out by executing material nonlinear analysis with an FEM-based computer program, whose predictive performance was calibrated based on the results of a previous experimental program.