Reinforced-Concrete Shear Walls Retrofitted Using Weakening and Self-Centering: Numerical Modeling

This paper investigates a novel retrofit strategy for code-deficient reinforced-concrete (RC) shear walls that are vulnerable to undesirable failure modes. The strategy combines weakening by partially cutting the wall base and self-centering by adding post-tensioning. RC walls in need of retrofit were analyzed under lateral cyclic loading using three-dimensional (3D) finite element (FE) modeling. Analyses were validated using test data from the literature on conventional walls that failed in flexure/shear and pure shear. These analyses were used to study the retrofit strategy. A parametric study was conducted to determine the working details of the retrofit method. A method was proposed to select retrofit parameters preliminarily. Retrofitted and original walls were compared. The sequence in which wall components failed was documented to identify changes in failure modes. Results of the analyses showed that although retrofitting reduced energy dissipation capacity, flexural displacements increased due to retrofit of poorly designed RC walls suffering from partial or pure shear failure. Retrofit resulted in fewer cracks, less intense concrete crushing, and a delayed fracture of transverse reinforcement. (C) 2020 American Society of Civil Engineers.