CFRP group effect and interaction between stirrups and strips on the NSM-shear strengthening of RC beams

Abstract

Available experimental research shows that the technique based on installing Carbon Fibre Reinforced Polymer (CFRP) strips into slits opened on the cover concrete of the beam’s lateral faces, designated as Near Surface Mounted (NSM), is very effective to increase the shear resistance of reinforced concrete (RC) beams. However, recent research has revealed that, in terms of NSM shear strengthening effectiveness, a detrimental effect can occur between existing steel stirrups and applied strips, as well as amongst the strips when the distance between strips, sf, is lower than a certain limit. In the present work, a test setup was developed and an experimental program was carried out to assess the influence of both sf and interaction between existing steel stirrups and strips on the shear strengthening of RC beams. The experimental program is described and the main results are presented and analyzed.