Seismic performance of RC columns retrofitted by CFRP wrapping ‘Study of the influencing parameters’

Abstract

The normative requirements on seismic performance of flexural compressed columns are translated through the criteria of stiffness, strength and ductility. It is well known that FRP external confinement is a very effective retrofitting technique for strengthening reinforced concrete columns (RC) subjected to static or seismic loads. A parametric study illustrating the influence of the main parameters, such as number of CFRP layers, concrete strength, longitudinal reinforcement ratio, axial load ratio and CFRP reinforcement ratio on\xa0the sectional behaviour and the structural slenderness on the global behaviour was conducted. The nonlinear (NL) sectional analysis based on fibre elements was conducted, while the NL global response was obtained using the NL Pushover analysis. The investigation obtained results permit to highlight the influence of the considered parameters through the evaluation of the registered strength and deformation gains. It was found that axial load and concrete strength are the most influencing the sectional performances despite the amount of CFRP wrapping. The NL RC columns behaviour depends intimately on the slenderness, the axial load and the CFRP ratio. The NL sectional and global adopted models were then calibrated with experimental results found within specific literature. It was concluded that the numerical NL models can retrace satisfactory the NL behaviour. More relevant conclusions regarding the conjugate influence of the CFRP sheets and the considered parameters were formulated and practical recommendations for the use of the CFRP external wrapping were established.