Hybrid CFRP-based strengthening technique to increase the flexural resistance and concrete confinement of RC columns submitted to axial and cyclic lateral loading

摘要

A strengthening technique that combines carbon fibre reinforced polymer (CFRP)laminates and strips of wet lay-up CFRP sheet was used to increase the flexural resistance and theenergy dissipation capacity of square cross-section columns of very low concrete strength submittedto constant axial compressive force and cyclic lateral loading. The laminates, applied according to theNear Surface Mounted (NSM) technique, have the purpose of increasing the flexural resistance of thecolumns, while the CFRP sheet installed as a localized jacket in the plastic hinge has the aim ofincreasing the concrete confinement and avoid the buckling and the debonding of the laminates. Inspite of the 8 MPa of average concrete compressive strength used to manufacture the columns, thehybrid strategy provided an average increase of about 46 % in terms of load carrying capacity, evenwhen applied in columns that had already been tested and presented intensives damages. Theexperimental program is described and the main results are presented and analyzed.