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 Near Surface Mounted (NSM) technique has high potential to increase 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 opened onto the top concrete cover at the intermediate supports and in the bottom concrete cover in the tensile zones. However, the linear-elastic behaviour of the CFRP laminates, and the possibility of occurring premature detachment of the concrete cover that includes these laminates can compromise, not only the flexural strengthening effectiveness of the NSM technique, but also the moment redistribution and the ductility performance of this type of structures. To evaluate the influence of the concrete strength class, the percentage of existing longitudinal tensile reinforcement and the percentage of CFRP on the strengthening effectiveness, moment redistribution capacity and ductility performance, a parametric study was carried out by executing material nonlinear analysis with a FEM-based computer program, which predictive performance was calibrated using the results of a previous experimental program.