Exploring NSM technique for torsional strengthening of tubular type RC structures

Abstract

The present paper explores, by advanced numerical simulations, the potentialities of the Near Surface Mounted (NSM) technique for the torsional strengthening of thin walled tubular type reinforced con-crete (RC) elements. According to this technique, fibre reinforced polymer (FRP) laminates are intro-duced into thin grooves opened on the concrete cover of the RC elements. A 3D multidirectional smeared crack model available in FEMIX computer code is used for the numerical simulations, and its predictive performance for capturing the behaviour of this type of elements was assessed by simulating experimental tests available in the literature. This model was then used to determine the influence of the variation of longitudinal reinforcement, transverse reinforcement and the concrete compressive strength on the torsional behaviour of thin walled tubular RC elements, with the focus on torque-angle of rotation response. The effect of the variation of the FRP’s modulus of elasticity is also investigated. The results allow to conclude that the proposed NSM strengthening technique is effective in increasing the stiffness and the load carrying capacity, as well as in arresting crack propagation of the strengthened tubular RC elements.