Near surface mounted CFRP strips for the flexural strengthening of RC columns: Experimental and numerical research

In this work, a strengthening technique based on near surface mounted (NSM) carbon fibre laminate strips bonded into slits opened on the concrete cover is used to improve the flexural capacity of columns subjected to bending and compression. This technique avoids the occurrence of the peeling phenomenon, is able to mobilize the full strengthening capacity of the strips, and provides higher protection against fire and acts of vandalism. We describe the adopted strengthening technique and report the experimental characterization of the materials involved in the strengthening process. The results obtained in two series of reinforced concrete columns, subjected to axial compression and lateral cyclic loading, show that a significant increase on the load carrying capacity can be achieved by using the NSM technique. Cyclic material constitutive laws were implemented in a finite element program and the tests with reinforced concrete columns strengthened with the NSM technique were numerically simulated under cyclic loading. These numerical simulations reproduce the experimental load–displacement diagrams satisfactorily.