Effect of confining of boundary elements of slender RC shear wall by FRP composites and stirrups

Existing concrete shear walls may be considered vulnerable for continuing service life due to changes in the seismic codes requirements, subjecting to intensive dynamic loads such as earthquake or explosion, and damages due to some local destructive loads. A review on the previous studies shows that despite the squat walls, very limited analytical and/or experimental studies have been already conducted on the FRP strengthening of slender RC shear walls under monotonic loading. In this paper the main focus is on the confinement of the boundary elements of shear walls with FRP composites and its effect on flexural behaviour of the wall. Nonlinear finite element analysis is performed on two shear wall specimens using damage plasticity model and considering tension stiffening effect. Results of the current study showed the superior effectiveness of strengthening FRP composite layers on ductile behaviour of concrete shear walls; i.e. the confinement of the boundary elements with FRP increased the ultimate displacement under almost constant load up to 50%. Furthermore, the results showed that it is sufficient to apply the FRP layers only on the boundary elements in the plastic hinge region of the wall.